graft: warn when -r is combined with revisions as positional arguments

The behaviour in this case is undefined. Instead of silently doing something
"random" and surprising, at least issue a warning.

(This should perhaps be considered a "deprecation" and turned into an error in
a future release.)

mercurial/commands.py

@@ -3889,6 +3889,10 b' def graft(ui, repo, *revs, **opts):'
         return _dograft(ui, repo, *revs, **opts)
 
 def _dograft(ui, repo, *revs, **opts):
+    if revs and opts['rev']:
+        ui.warn(_('warning: inconsistent use of --rev might give unexpected '
+                  'revision ordering!\n'))
+
     revs = list(revs)
     revs.extend(opts['rev'])
 

tests/test-graft.t

@@ -62,6 +62,7 b' Specify revisions with -r:'
   [255]
 
   $ hg graft -r 1 2
+  warning: inconsistent use of --rev might give unexpected revision ordering!
   skipping ancestor revision 2:5c095ad7e90f
   skipping ancestor revision 1:5d205f8b35b6
   [255]