histedit: prevent parent guessed via --outgoing from being a revset (issue3770)

If the binary hash of the parent node guessed via --outgoing happened
to contain a special revset character (":" was specified in the bug),
the revset parser would abort. Hexlifying the node before passing it
to the revsingle call should fix that.

hgext/histedit.py

@@ -454,8 +454,12 b' def histedit(ui, repo, *parent, **opts):'
         if revs:
             revs = [repo.lookup(rev) for rev in revs]
 
-        parent = discovery.findcommonoutgoing(
-            repo, other, [], force=opts.get('force')).missing[0:1]
+        # hexlify nodes from outgoing, because we're going to parse
+        # parent[0] using revsingle below, and if the binary hash
+        # contains special revset characters like ":" the revset
+        # parser can choke.
+        parent = [node.hex(n) for n in discovery.findcommonoutgoing(
+            repo, other, [], force=opts.get('force')).missing[0:1]]
     else:
         if opts.get('force'):
             raise util.Abort(_('--force only allowed with --outgoing'))