Fix embarrassing "git log --follow" bug

[Linus Torvalds <torvalds@linux-foundation.org>]

It turns out that I completely broke "git log --follow" with my recent 
patch to revision.c ("Fix revision log diff setup, avoid unnecessary diff 
generation", commit b7bb760d5ed4881422673d32f869d140221d3564).

Why? Because --follow obviously requires the diff machinery to function, 
exactly the same way pickaxe does.

So everybody is away right now, but considering that nobody even noticed 
this bug, I don't think it matters. But for the record, here's the trivial 
one-liner fix (well, two, since I also fixed the comment).

Because of the nature of the bug, if you ask for patches when following 
(which is one of the things I normally do), the bug is hidden, because 
then the request for diff output will automatically also enable the diffs 
themselves.

So while "git log --follow <filename>" didn't work, adding a "-p" 
magically made it work again even without this fix.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 revision.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/revision.c b/revision.c
index 5d294be..e76da0d 100644
--- a/revision.c
+++ b/revision.c
@@ -1241,8 +1241,8 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 	if (revs->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT)
 		revs->diff = 1;
 
-	/* Pickaxe needs diffs */
-	if (revs->diffopt.pickaxe)
+	/* Pickaxe and rename following needs diffs */
+	if (revs->diffopt.pickaxe || revs->diffopt.follow_renames)
 		revs->diff = 1;
 
 	if (revs->topo_order)