diff -r 91f3ac205816 -r 1093ad1e8903 mercurial/phases.py
--- a/mercurial/phases.py	Fri Jun 01 12:37:18 2012 -0700
+++ b/mercurial/phases.py	Fri Jun 01 12:45:16 2012 -0700
@@ -189,7 +189,7 @@
                 if roots:
                     for rev in roots:
                         revs[rev] = phase
-                    for rev in repo.changelog.descendants(*roots):
+                    for rev in repo.changelog.descendants(roots):
                         revs[rev] = phase
             self._phaserevs = revs
         return self._phaserevs