Code review comment for lp:~mzanetti/unity8/update-inputinfo

Here's the backtrace:

[Thread 0x7fffe09d9700 (LWP 30234) exited]
*** Error in `/usr/lib/x86_64-linux-gnu/qt5/bin/qmltestrunner': free(): invalid pointer: 0x00007fffda0b6380 ***
[New Thread 0x7fffd355d700 (LWP 30235)]
[New Thread 0x7fffeb5df700 (LWP 30233)]

Program received signal SIGABRT, Aborted.
0x00007ffff7a44267 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:55
55 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0 0x00007ffff7a44267 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:55
#1 0x00007ffff7a45eca in __GI_abort () at abort.c:89
#2 0x00007ffff7a87c53 in __libc_message (do_abort=do_abort@entry=1, fmt=fmt@entry=0x7ffff7ba01a8 "*** Error in `%s': %s: 0x%s ***\n") at ../sysdeps/posix/libc_fatal.c:175
#3 0x00007ffff7a8fc69 in malloc_printerr (ptr=<optimized out>, str=0x7ffff7b9c2fa "free(): invalid pointer", action=1) at malloc.c:4965
#4 _int_free (av=<optimized out>, p=<optimized out>, have_lock=0) at malloc.c:3834
#5 0x00007ffff7a9389c in __GI___libc_free (mem=<optimized out>) at malloc.c:2950
#6 0x00007ffff631de91 in QQmlType::SingletonInstanceInfo::destroy(QQmlEngine*) () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#7 0x00007ffff62f4373 in QQmlEngine::~QQmlEngine() () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#8 0x00007ffff62f4499 in QQmlEngine::~QQmlEngine() () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#9 0x00007ffff6be869c in QObjectPrivate::deleteChildren() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#10 0x00007ffff6bf2d03 in QObject::~QObject() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#11 0x00007ffff668a959 in QQuickWindow::~QQuickWindow() () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#12 0x00007ffff6739f79 in QQuickView::~QQuickView() () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#13 0x00007ffff7fbf393 in quick_test_main(int, char**, char const*, char const*) () from /usr/lib/x86_64-linux-gnu/libQt5QuickTest.so.5
#14 0x00007ffff7a2fa40 in __libc_start_main (main=0x4005d0, argc=7, argv=0x7fffffffd9e8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffd9d8) at libc-start.c:289
#15 0x0000000000400619 in ?? ()