Merge lp:~blake-rouse/maas/fix-1499749-1.8 into lp:maas/1.8

[Blake Rouse]

checksummer is no longer in the simplestreams.util module.

This plays it defensively and checks both the simplestreams.util and simplestreams.checksum_util modules for checksummer.

Backport: https://code.launchpad.net/~allenap/maas/simplestreams-moved-checksummer/+merge/272368

[Blake Rouse (blake-rouse)]

Self-approving backport.

review: Approve

=== modified file 'src/maasserver/bootresources.py'
--- src/maasserver/bootresources.py	2015-06-02 08:46:21 +0000
+++ src/maasserver/bootresources.py	2015-09-25 14:39:44 +0000
@@ -98,6 +98,12 @@
 from twisted.python import log
 
 
+try:
+    from simplestreams.checksum_util import checksummer
+except ImportError:
+    from simplestreams.util import checksummer
+
+
 maaslog = get_maas_logger("bootresources")
 
 # Used by maasserver.middleware.AccessMiddleware to allow
@@ -653,7 +659,7 @@
         """Writes the data from the given reader, into the object storage
         for the given `BootResourceFile`."""
         ident = self.get_resource_file_log_identifier(rfile)
-        cksummer = sutil.checksummer(
+        cksummer = checksummer(
             {'sha256': rfile.largefile.sha256})
         maaslog.debug("Finalizing boot image %s.", ident)