morestatus: check whether the conflict message is None before printing

There are cases like bisect when the conflict message can be None. So we make
sure that we don't print None in that case.

Thanks to Martin for catching this.

Differential Revision: https://phab.mercurial-scm.org/D461

mercurial/cmdutil.py

@@ -673,6 +673,7 def morestatus(repo, fm):
         statemsg = _('The repository is in an unfinished *%s* state.') % state
         fm.write('statemsg', '%s\n',  _commentlines(statemsg), label=label)
         conmsg = _conflictsmsg(repo)
+        if conmsg:
         fm.write('conflictsmsg', '%s\n', conmsg, label=label)
         if helpfulmsg:
             helpmsg = helpfulmsg()

tests/test-bisect.t

@@ -187,7 +187,6 bisect test
   $ hg status -v
   # The repository is in an unfinished *bisect* state.
   
-  None
   # To mark the changeset good:    hg bisect --good
   # To mark the changeset bad:     hg bisect --bad
   # To abort:                      hg bisect --reset