diff -r a38a99c74ad4 -r b6c2543e1dd8 mercurial/context.py
--- a/mercurial/context.py	Thu Oct 04 10:30:05 2018 -0700
+++ b/mercurial/context.py	Thu Oct 04 10:38:55 2018 -0700
@@ -909,7 +909,7 @@
        filerevision convenient."""
     def __init__(self, repo, path, changeid=None, fileid=None,
                  filelog=None, changectx=None):
-        """changeid can be a changeset revision, node, or tag.
+        """changeid must be a revision number, if specified.
            fileid can be a file revision or node."""
         self._repo = repo
         self._path = path