[PATCH] commit: skip discarding the index if there is no pre-commit hook

[Kevin Willford]

If there is not a pre-commit hook, there is no reason to discard
the index and reread it.

This change checks to presence of a pre-commit hook and then only
discards the index if there was one.

Signed-off-by: Kevin Willford <kewi...@microsoft.com>
---
 builtin/commit.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index e7a2cb6285..443949d87b 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -671,12 +671,22 @@ static int prepare_to_commit(const char *index_file, 
const char *prefix,
        const char *hook_arg2 = NULL;
        int clean_message_contents = (cleanup_mode != CLEANUP_NONE);
        int old_display_comment_prefix;
+       const char *precommit_hook = NULL;
 
        /* This checks and barfs if author is badly specified */
        determine_author_info(author_ident);
 
-       if (!no_verify && run_commit_hook(use_editor, index_file, "pre-commit", 
NULL))
-               return 0;
+
+       if (!no_verify) {
+               /*
+                * Check to see if there is a pre-commit hook
+                * If there not one we can skip discarding the index later on
+                */
+               precommit_hook = find_hook("pre-commit");
+               if (precommit_hook &&
+                   run_commit_hook(use_editor, index_file, "pre-commit", NULL))
+                       return 0;
+       }
 
        if (squash_message) {
                /*
@@ -940,12 +950,15 @@ static int prepare_to_commit(const char *index_file, 
const char *prefix,
                return 0;
        }
 
-       /*
-        * Re-read the index as pre-commit hook could have updated it,
-        * and write it out as a tree.  We must do this before we invoke
-        * the editor and after we invoke run_status above.
-        */
-       discard_cache();
+       if (!no_verify && precommit_hook) {
+               /*
+                * Re-read the index as pre-commit hook could have updated it,
+                * and write it out as a tree.  We must do this before we invoke
+                * the editor and after we invoke run_status above.
+                */
+               discard_cache();
+       }
+
        read_cache_from(index_file);
        if (update_main_cache_tree(0)) {
                error(_("Error building trees"));
-- 
2.14.0.rc0.286.g44127d70e4