[PATCH v2] mergetool: Remove explicit references to /dev/tty

[Charles Bailey <charles@hashpling.org>]

mergetool used /dev/tty to switch back to receiving input from the user
via inside a block with a redirected stdin.

This harms testability, so change mergetool to save its original stdin
to an alternative fd in this block and restore it for those sub-commands
that need the original stdin.

Includes additional compatibility fix from Jonathan Nieder.

Tested-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Charles Bailey <charles@hashpling.org>
---

Now works on ksh as well as bash and dash.

 git-mergetool--lib.sh |    2 +-
 git-mergetool.sh      |    7 +++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 51dd0d6..b5e1943 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -35,7 +35,7 @@ check_unchanged () {
 		while true; do
 			echo "$MERGED seems unchanged."
 			printf "Was the merge successful? [y/n] "
-			read answer < /dev/tty
+			read answer
 			case "$answer" in
 			y*|Y*) status=0; break ;;
 			n*|N*) status=1; break ;;
diff --git a/git-mergetool.sh b/git-mergetool.sh
index bd7ab02..165b700 100755
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -279,6 +279,9 @@ files_to_merge() {
 if test $# -eq 0 ; then
     cd_to_toplevel
 
+    # Save original stdin
+    exec 3<&0
+
     if test -e "$GIT_DIR/MERGE_RR"
     then
 	rerere=true
@@ -296,10 +299,10 @@ if test $# -eq 0 ; then
     while IFS= read i
     do
 	if test $last_status -ne 0; then
-	    prompt_after_failed_merge < /dev/tty || exit 1
+	    prompt_after_failed_merge <&3 || exit 1
 	fi
 	printf "\n"
-	merge_file "$i" < /dev/tty > /dev/tty
+	merge_file "$i" <&3
 	last_status=$?
 	if test $last_status -ne 0; then
 	    rollup_status=1
-- 
1.7.2.2.110.gf04b9.dirty