[PATCH] checkout -f: do not leave untracked working tree files.

[Junio C Hamano <junkio@cox.net>]

Earlier we did not consider untracked working tree files
"precious", but we have always considered them fair game to
clobber.  These days, branch switching by read-tree is more
careful and tries to protect untracked working tree files.  This
caused the following workflow to stop working:

	git checkout one-branch-with-file-F
	git checkout -f another-without-file-F
	git pull . one-branch-with-file-F

Because the second checkout leaves F from the previous state as
untracked file in the working tree, the merge would fail, trying
to protect F from being clobbered.

This changes "git checkout -f" to remove working tree files that
are known to git in the switched-from state but do not exist in
the switched-to state, borrowing the same logic from "reset --hard".

Signed-off-by: Junio C Hamano <junkio@cox.net>
---

 * I am going to bed without trying this out since it is very
   late tonight.  Might be in "pu" or "next" tomorrow depending
   on my mood.  If this works out for Jeff, I can simply drop
   the "core.oktoclobber = ask" patch from my topics -- although
   I kind of liked that one ;-).

 git-checkout.sh |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/git-checkout.sh b/git-checkout.sh
index 564117f..77c2593 100755
--- a/git-checkout.sh
+++ b/git-checkout.sh
@@ -137,8 +137,7 @@ # what we already had
 
 if [ "$force" ]
 then
-    git-read-tree --reset $new &&
-	git-checkout-index -q -f -u -a
+    git-read-tree --reset -u $new
 else
     git-update-index --refresh >/dev/null
     merge_error=$(git-read-tree -m -u $old $new 2>&1) || (
-- 
1.4.0.g59268