commands: don't check for merge.update() truthiness

commands: don't check for merge.update() truthiness

AFAICT ``stats`` is always a tuple in these cases. We don't
need to check if the variable has a truthy value.

Differential Revision: https://phab.mercurial-scm.org/D2691

--- a/hgext/rebase.py	Wed Mar 07 19:57:50 2018 -0800
+++ b/hgext/rebase.py	Mon Mar 05 00:18:07 2018 -0500
@@ -488,7 +488,7 @@
                 with ui.configoverride(overrides, 'rebase'):
                     stats = rebasenode(repo, rev, p1, base, self.collapsef,
                                        dest, wctx=self.wctx)
-                    if stats and stats[3] > 0:
+                    if stats[3] > 0:
                         if self.wctx.isinmemory():
                             raise error.InMemoryMergeConflictsError()
                         else:

--- a/mercurial/commands.py	Wed Mar 07 19:57:50 2018 -0800
+++ b/mercurial/commands.py	Mon Mar 05 00:18:07 2018 -0500
@@ -2306,7 +2306,7 @@
             finally:
                 repo.ui.setconfig('ui', 'forcemerge', '', 'graft')
             # report any conflicts
-            if stats and stats[3] > 0:
+            if stats[3] > 0:
                 # write out state for --continue
                 nodelines = [repo[rev].hex() + "\n" for rev in revs[pos:]]
                 repo.vfs.write('graftstate', ''.join(nodelines))