stash: avoid dashed invocation

The invocation of dashed Git commands was rightfully deprecated a long
time ago. We failed to heed that deprecation ourselves, but it is never
too late...

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

git-stash.sh

@@ -502,7 +502,7 @@ apply_stash () {
 
 	if test -n "$u_tree"
 	then
-		GIT_INDEX_FILE="$TMPindex" git-read-tree "$u_tree" &&
+		GIT_INDEX_FILE="$TMPindex" git read-tree "$u_tree" &&
 		GIT_INDEX_FILE="$TMPindex" git checkout-index --all &&
 		rm -f "$TMPindex" ||
 		die "$(gettext "Could not restore untracked files from stash")"