py3: use %d to format an int

Avoids a TypeError under py3.  Fortunately this is very much an edge case since
it requires the user to have deliberately created a local tag of the form
'D\d+' that isn't truthful.

Differential Revision: https://phab.mercurial-scm.org/D7215

hgext/phabricator.py

@@ -441,7 +441,7 b' def getoldnodedrevmap(repo, nodelist):'
                 )
                 unfi.ui.warn(
                     _(
-                        b'D%s: local tag removed - does not match '
+                        b'D%d: local tag removed - does not match '
                         b'Differential history\n'
                     )
                     % drev