[PATCH] localrepo: correct docstring of filectx()

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1543153194 -32400
#      Sun Nov 25 22:39:54 2018 +0900
# Node ID 3cba13b2e62284f3bd4ed3219864b7418a99f596
# Parent  cfaf3843491bde30916b89180d5f67561a22da28
localrepo: correct docstring of filectx()

The same reason as b6c2543e1dd8. It can't be any changeset specifiers but
revision number.

diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1587,7 +1587,7 @@ class localrepository(object):
                         self.dirstate.copy(None, f)
 
     def filectx(self, path, changeid=None, fileid=None, changectx=None):
-        """changeid can be a changeset revision, node, or tag.
+        """changeid must be a changeset revision, if specified.
            fileid can be a file revision or node."""
         return context.filectx(self, path, changeid, fileid,
                                changectx=changectx)