[MERGE][#297014] Add a flag to suppress errors from abort_write_group

[Martin Pool]

Martin Pool has voted tweak.
Status is now: Conditionally approved
Comment:
@@ -521,7 +522,15 @@
          if self._write_group is not self.get_transaction():
              # has an unlock or relock occured ?
              raise errors.BzrError('mismatched lock context and write 
group.')
-        self._abort_write_group()
+        try:
+            self._abort_write_group()
+        except Exception, exc:
+            self._write_group = None
+            if not suppress_errors:
+                raise
+            mutter('abort_write_group failed')
+            log_exception_quietly()
+            note('bzr: ERROR (ignored): %s', exc)
          self._write_group = None

      def _abort_write_group(self):

Maybe we should log, and arguably even print, the error in every case, 
even if we're going to re-raise it.

Also I'd like know that this has been tested interactively, eg by doing 
a push over ssh and killing the ssh subprocess.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C20081112041247.GA29558%40steerpike.home.puzzling.org%3E
Project: Bazaar