--- a/mercurial/commands.py	Thu Dec 17 15:03:45 2015 +0000
+++ b/mercurial/commands.py	Thu Dec 17 15:05:25 2015 +0000
@@ -1347,6 +1347,8 @@
         if dest:
             raise error.Abort(_("--all is incompatible with specifying "
                                 "a destination"))
+        if opts.get('base'):
+            ui.warn(_("ignoring --base because --all was specified\n"))
         base = ['null']
     else:
         base = scmutil.revrange(repo, opts.get('base'))