recur vs recursive: help testing without touching too many stuff.

During git-merge-recur development, you could set an environment
variable GIT_USE_RECUR_FOR_RECURSIVE to use WIP recur in place
of the recursive strategy.

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

git-rebase.sh

@@ -35,7 +35,13 @@ If you would prefer to skip this patch, instead run \"git rebase --skip\".
 To restore the original branch and stop rebasing run \"git rebase --abort\".
 "
 unset newbase
-strategy=recur
+case "${GIT_USE_RECUR_FOR_RECURSIVE}" in
+'')
+	strategy=recursive ;;
+?*)
+	strategy=recur ;;
+esac
+
 do_merge=
 dotest=$GIT_DIR/.dotest-merge
 prec=4
@@ -198,6 +204,11 @@ do
 	shift
 done
 
+case "$strategy,${GIT_USE_RECUR_FOR_RECURSIVE}" in
+recursive,?*)
+	strategy=recur ;;
+esac
+
 # Make sure we do not have .dotest
 if test -z "$do_merge"
 then
@@ -292,7 +303,7 @@ then
 	exit $?
 fi
 
-if test "@@NO_PYTHON@@" && test "$strategy" = "recur"
+if test "@@NO_PYTHON@@" && test "$strategy" = "recursive"
 then
 	die 'The recursive merge strategy currently relies on Python,
 which this installation of git was not configured with.  Please consider