phases: fix missing "error" module import (issue3707)

mercurial/phases.py

@@ -103,7 +103,7 b' Note: old client behave as a publishing '
 import errno
 from node import nullid, nullrev, bin, hex, short
 from i18n import _
-import util
+import util, error
 import obsolete
 
 allphases = public, draft, secret = range(3)

tests/test-phases.t

@@ -337,8 +337,17 b' test that phase are displayed in log at '
   description:
   A
   
+
+
+(Issue3707)
+test invalid phase name
+
+  $ mkcommit I --config phases.new-commit='babar'
+  transaction abort!
+  rollback completed
+  abort: phases.new-commit: not a valid phase name ('babar')
+  [255]
   
-
 Test phase command
 ===================