log: fix --follow null parent not to include revision 0 If p1 is null, ':.' is translated as '0:null'. But rangeset can't handle null, only revision 0 was visible. Because 'null' should not be listed implicitly, "log --follow" (without -r) should be empty if p1 is null. Test of "hg grep -f" is added for cmdutil.walkchangerevs().

--- a/tests/test-grep.t	Fri Feb 06 00:22:20 2015 +0900
+++ b/tests/test-grep.t	Fri Feb 06 21:53:39 2015 +0900
@@ -82,6 +82,10 @@
   port:1:2:+:eggs:export
   port:0:1:+:spam:import
 
+  $ hg up -q null
+  $ hg grep -f port
+  [1]
+
   $ cd ..
   $ hg init t2
   $ cd t2