mercurial/commands.py

--- a/mercurial/commands.py	Fri Jun 26 14:33:34 2015 -0700
+++ b/mercurial/commands.py	Sun Jun 28 18:39:58 2015 -0400
@@ -4064,7 +4064,9 @@
             if bm:
                 output.append(bm)
     else:
-        if not rev:
+        ctx = scmutil.revsingle(repo, rev, None)
+
+        if ctx.rev() is None:
             ctx = repo[None]
             parents = ctx.parents()
             changed = ""
@@ -4079,7 +4081,6 @@
                 output.append("%s%s" %
                   ('+'.join([str(p.rev()) for p in parents]), changed))
         else:
-            ctx = scmutil.revsingle(repo, rev)
             if default or id:
                 output = [hexfunc(ctx.node())]
             if num: