[PATCH] Improvement to only call Git Credential Helper once

[Kyle Hubert <khubert@gmail.com>]

When calling the Git Credential Helper that is set in the git config,
the get command can return a credential. Git immediately turns around
and calls the store command, even though that credential was just
retrieved by the Helper. This creates two side effects. First of all,
if the Helper requires a passphrase, the user has to type it in
twice. Secondly, if the user has a number of helpers, this retrieves
the credential from one service and writes it to all services.

This commit introduces a new field in the credential struct that
detects when the credential was retrieved using the Helper, and early
exits when called to store the credential.
---
 credential.c | 8 +++++++-
 credential.h | 3 ++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/credential.c b/credential.c
index 62be651b0..79bf62d49 100644
--- a/credential.c
+++ b/credential.c
@@ -280,8 +280,10 @@ void credential_fill(struct credential *c)

  for (i = 0; i < c->helpers.nr; i++) {
  credential_do(c, c->helpers.items[i].string, "get");
- if (c->username && c->password)
+ if (c->username && c->password) {
+ c->retrieved = 1;
  return;
+ }
  if (c->quit)
  die("credential helper '%s' told us to quit",
      c->helpers.items[i].string);
@@ -300,6 +302,10 @@ void credential_approve(struct credential *c)
  return;
  if (!c->username || !c->password)
  return;
+ if (c->retrieved) {
+ c->approved = 1;
+ return;
+ }

  credential_apply_config(c);

diff --git a/credential.h b/credential.h
index 6b0cd16be..d99df2f52 100644
--- a/credential.h
+++ b/credential.h
@@ -8,7 +8,8 @@ struct credential {
  unsigned approved:1,
  configured:1,
  quit:1,
- use_http_path:1;
+ use_http_path:1,
+ retrieved:1;

  char *username;
  char *password;