Merge branch 'jc/sane-grep'

Recent versions of GNU grep is pickier than before to decide if a
file is "binary" and refuse to give line-oriented hits when we
expect it to, unless explicitly told with "-a" option.  As our
scripted Porcelains use sane_grep wrapper for line-oriented data,
even when the line may contain non-ASCII payload we took from
end-user data, use "grep -a" to implement sane_grep wrapper when
using an implementation of "grep" that takes the "-a" option.

* jc/sane-grep:
  rebase-i: clarify "is this commit relevant?" test
  sane_grep: pass "-a" if grep accepts it

git-rebase--interactive.sh

@@ -1233,7 +1233,8 @@ then
 	git rev-list $revisions |
 	while read rev
 	do
-		if test -f "$rewritten"/$rev && test "$(sane_grep "$rev" "$state_dir"/not-cherry-picks)" = ""
+		if test -f "$rewritten"/$rev &&
+		   ! sane_grep "$rev" "$state_dir"/not-cherry-picks >/dev/null
 		then
 			# Use -f2 because if rev-list is telling us this commit is
 			# not worthwhile, we don't want to track its multiple heads,