SMB connection is started choosing from Gnome's 'places' a bookmark with remembered password to connect.

stack trace doing gdb --pid=$PID, and then:
thread apply all bt full

---------------------------------------------------------------
Thread 2 (Thread 0x7fb0d0c5f710 (LWP 20557)):
#0  dbus_pending_call_block (pending=0x7fb0cc075cd0) at dbus-pending-call.c:703
        __FUNCTION__ = "dbus_pending_call_block"
#1  0x0000003b65408a03 in gkr_operation_block (op=0x7fb0cc078040) at gkr-operation.c:372
        __PRETTY_FUNCTION__ = "gkr_operation_block"
#2  0x000000000041b975 in g_vfs_keyring_lookup_password (username=0x1b5fa70 "nmt", host=0x1b5f3f0 "192.168.2.4", domain=0x0, 
    protocol=<value optimized out>, object=0x0, authtype=<value optimized out>, port=0, username_out=0x7fb0d0c5e2e8, domain_out=0x7fb0d0c5e2e0, 
    password_out=0x7fb0d0c5e2f0) at gvfskeyring.c:61
        pwd_data = 0x1b5fa70
        result = <value optimized out>
        plist = <value optimized out>
#3  0x00000000004098a0 in auth_callback (context=<value optimized out>, server_name=<value optimized out>, share_name=<value optimized out>, 
    domain_out=0x7fb0d0c5e580 "MYGROUP", domainmaxlen=<value optimized out>, username_out=0x7fb0d0c5e480 "nmt", unmaxlen=256, 
    password_out=0x7fb0d0c5e380 "", pwmaxlen=256) at gvfsbackendsmb.c:203
        in_keyring = 0
        backend = 0x1b5e020
        ask_password = <value optimized out>
        ask_user = <value optimized out>
        ask_domain = <value optimized out>
        handled = <value optimized out>
        abort = <value optimized out>
#4  0x00007fb0d755419a in SMBC_call_auth_fn (ctx=0x7fb0cc030ea0, context=<value optimized out>, server=<value optimized out>, share=<value optimized out>, 
    pp_workgroup=0x7fb0d0c5ebe0, pp_username=0x7fb0d0c5ebf0, pp_password=0x7fb0d0c5ebe8) at libsmb/libsmb_server.c:115
        workgroup = "MYGROUP\000\200\071@S;\000\000\000\240MPװ\177\000\000`\226\327װ\177\000\000\250\001\000\000\001\000\000\000\377\377\377\377\000\000\000\000\005\000\000\000\000\000\000\000\005\000\000\000\000\000\000\000x`b", '\000' <repeats 13 times>"\360, .\a̰\177\000\000\220\067\a̰\177\000\000\000\000\000\000\000\000\000\000\341\345\200P;\000\000\000\005", '\000' <repeats 15 times>, "\005\000\000\000\260\177\000\000\240MPװ\177\000\000\030\350\305а\177\000\000\360.\a̰\177\000\000`/\a̰\177\000\000PG\a̰\177\000\000`/\a̰\177\000\000\245R\201P;\000\000\000p\224@\000\000\000\000\000PG\a̰\177\000\000`/\a̰\177\000\000\360.\a̰\177\000\000`[\a̰\177\000\000\220\067\a̰\177\000\000\360\353\305а\177\000\000\350 \242P;"...
        username = "nmt", '\000' <repeats 252 times>
        password = '\000' <repeats 255 times>
        auth_with_context_fn = <value optimized out>
#5  0x00007fb0d7554400 in SMBC_find_server (ctx=0x7fb0cc030ea0, context=0x7fb0cc075b60, server=0x7fb0cc072ef0 "192.168.2.4", share=0x7fb0cc072f60 "share", 
    pp_workgroup=0x7fb0d0c5ebe0, pp_username=0x7fb0d0c5ebf0, pp_password=0x7fb0d0c5ebe8) at libsmb/libsmb_server.c:175
        srv = <value optimized out>
        auth_called = <value optimized out>
#6  0x00007fb0d75544ed in SMBC_server_internal (ctx=<value optimized out>, context=0x7fb0cc075b60, connect_if_not_found=true, 
    server=0x7fb0cc072ef0 "192.168.2.4", share=<value optimized out>, pp_workgroup=0x7fb0d0c5ebe0, pp_username=0x7fb0d0c5ebf0, pp_password=0x7fb0d0c5ebe8, 
    in_cache=0x7fb0d0c5eb1f) at libsmb/libsmb_server.c:267
        srv = 0x0
        workgroup = 0x0
        c = 0x0
        called = {name = "\300/\a̰\177\000\000\300/\a̰\177\000", 
          scope = "`[\a̰\177", '\000' <repeats 34 times>, "\001\000\000\000\000\000\000\000\200\000\000\000\000\000\000\000\006\000\000\000|\000\000", 
          name_type = 119}
        calling = {name = "\340\023\004̰\177\000\000;s\223װ\177\000", 
          scope = "\200\023\004̰\177\000\000R\313\307P;\000\000\000(\000\000\000\000\000\000\000p\f\025\350\000\000\000\000P6\a̰\177\000\000\340\023\004̰\177\000\000\000\000\000\000\000\000\000\000\300/\a̰\177\000", name_type = 8}
        ss = {ss_family = 2, __ss_align = 0, __ss_padding = '\000' <repeats 111 times>}
        tried_reverse = 0
        port_try_first = <value optimized out>
        port_try_next = <value optimized out>
        is_ipc = <value optimized out>
        fs_attrs = 0
        username_used = <value optimized out>
        status = <value optimized out>
        newserver = <value optimized out>
        newshare = <value optimized out>
        __FUNCTION__ = "SMBC_server_internal"
#7  0x00007fb0d75551de in SMBC_server (ctx=<value optimized out>, context=0x7fb0cc075b60, connect_if_not_found=<value optimized out>, 
    server=0x7fb0cc072ef0 "192.168.2.4", share=0x7fb0cc072f60 "share", pp_workgroup=0x7fb0d0c5ebe0, pp_username=0x7fb0d0c5ebf0, pp_password=0x7fb0d0c5ebe8)
    at libsmb/libsmb_server.c:670
        srv = 0x0
        in_cache = false
        __FUNCTION__ = "SMBC_server"
#8  0x00007fb0d75561e4 in SMBC_stat_ctx (context=0x7fb0cc075b60, fname=0x7fb0cc062370 "smb://192.168.2.4/share", st=0x7fb0d0c5ec80)
    at libsmb/libsmb_stat.c:168
        srv = 0x0
        server = 0x7fb0cc072ef0 "192.168.2.4"
        share = 0x7fb0cc072f60 "share"
        user = 0x7fb0cc073790 "iranzo"
        password = 0x7fb0cc0413e0 ""
        workgroup = 0x7fb0cc074750 "MYGROUP"
        path = 0x7fb0cc072e90 ""
        write_time_ts = {tv_sec = 5, tv_nsec = 0}
        access_time_ts = {tv_sec = 0, tv_nsec = 254753695201}
        change_time_ts = {tv_sec = 140397393603712, tv_nsec = 140397313621664}
        size = 0
        mode = 0
        ino = 0
        frame = <value optimized out>
        __FUNCTION__ = "SMBC_stat_ctx"
#9  0x000000000040b633 in do_mount (backend=<value optimized out>, job=0x1b5d030, mount_spec=<value optimized out>, mount_source=<value optimized out>, 
    is_automount=<value optimized out>) at gvfsbackendsmb.c:575
        op_backend = 0x1b5e020
        smb_context = 0x7fb0cc075b60
        st = {st_dev = 254761504384, st_ino = 254758341034, st_nlink = 140397393603864, st_mode = 0, st_uid = 1, st_gid = 0, __pad0 = 0, 
          st_rdev = 254766231095, st_size = 0, st_blksize = 2032, st_blocks = 0, st_atim = {tv_sec = 254790318144, tv_nsec = 32}, st_mtim = {
            tv_sec = 28597152, tv_nsec = 140397313525952}, st_ctim = {tv_sec = 254790318144, tv_nsec = 32}, __unused = {28692528, 28702464, 28692528}}
        uri = 0x7fb0cc062370 "smb://192.168.2.4/share"
        res = <value optimized out>
        display_name = <value optimized out>
        debug = <value optimized out>
        debug_val = <value optimized out>
        smb_mount_spec = 0x7fb0cc017ea0
        smbc_stat = <value optimized out>
#10 0x0000000000410ec2 in g_vfs_job_run (job=0x1b5d030) at gvfsjob.c:198
        class = 0x1b5f700
#11 0x0000003b5286702b in g_thread_pool_thread_proxy (data=<value optimized out>) at gthreadpool.c:315
        task = 0x1b5d030
        pool = 0x1b53390
#12 0x0000003b52865164 in g_thread_create_proxy (data=0x1b5cdf0) at gthread.c:1893
        thread = 0x1b5cdf0
        __PRETTY_FUNCTION__ = "g_thread_create_proxy"
#13 0x0000003b51406e11 in start_thread (arg=0x7fb0d0c5f710) at pthread_create.c:301
        __res = <value optimized out>
        pd = 0x7fb0d0c5f710
        now = <value optimized out>
        unwind_buf = {cancel_jmp_buf = {{jmp_buf = {140397393606416, 6505944271681342490, 140733309885504, 140397393606416, 0, 3, -6545876146535412710, 
                6503025618731256858}, mask_was_saved = 0}}, priv = {pad = {0x0, 0x0, 0x0, 0x0}, data = {prev = 0x0, cleanup = 0x0, canceltype = 0}}}
        not_first_call = <value optimized out>
        sp = <value optimized out>
        freesize = <value optimized out>
        __PRETTY_FUNCTION__ = "start_thread"
#14 0x0000003b50ce4a0d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115
No locals.

Thread 1 (Thread 0x7fb0d6bfa7c0 (LWP 20556)):
#0  0x0000003b50cdb283 in __poll (fds=<value optimized out>, nfds=<value optimized out>, timeout=<value optimized out>)
    at ../sysdeps/unix/sysv/linux/poll.c:87
        __arg2 = 7
        _a3 = -1
        _a1 = 28694848
        resultvar = <value optimized out>
        __arg3 = -1
        __arg1 = 28694848
        _a2 = 7
        resultvar = <value optimized out>
        oldtype = 0
        result = <value optimized out>
#1  0x0000003b5283f8f9 in g_main_context_poll (context=0x1b52be0, block=<value optimized out>, dispatch=<value optimized out>, self=<value optimized out>)
    at gmain.c:2904
        poll_func = 0x3b5284ca20 <IA__g_poll>
#2  g_main_context_iterate (context=0x1b52be0, block=<value optimized out>, dispatch=<value optimized out>, self=<value optimized out>) at gmain.c:2586
        max_priority = 2147483647
        timeout = -1
        some_ready = <value optimized out>
        nfds = 7
        allocated_nfds = <value optimized out>
        fds = 0x1b5d940
        __PRETTY_FUNCTION__ = "g_main_context_iterate"
#3  0x0000003b528400a5 in IA__g_main_loop_run (loop=0x1b53210) at gmain.c:2799
        self = 0x1b44520
        __PRETTY_FUNCTION__ = "IA__g_main_loop_run"
#4  0x000000000040c0de in daemon_main (argc=<value optimized out>, argv=<value optimized out>, max_job_threads=<value optimized out>, 
    default_type=0x41d883 "smb-share", mountable_name=<value optimized out>, first_type_name=0x41d883 "smb-share") at daemon-main.c:294
        var_args = {{gp_offset = 48, fp_offset = 0, overflow_arg_area = 0x7fff06f1a240, reg_save_area = 0x7fff06f1a1c0}}
        connection = <value optimized out>
        loop = <value optimized out>
        daemon = 0x1b53400
        derror = {name = 0x0, message = 0x0, dummy1 = 1, dummy2 = 0, dummy3 = 0, dummy4 = 0, dummy5 = 0, padding1 = 0x3b5285aca1}
        mount_spec = 0x0
        mount_source = <value optimized out>
        error = 0x0
        res = <value optimized out>
        type = <value optimized out>
#5  0x000000000040c36c in main (argc=4, argv=0x7fff06f1a338) at daemon-main-generic.c:39
No locals.
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