submodule: stop sanitizing config options

The point of having a whitelist of command-line config
options to pass to submodules was two-fold:

  1. It prevented obvious nonsense like using core.worktree
     for multiple repos.

  2. It could prevent surprise when the user did not mean
     for the options to leak to the submodules (e.g.,
     http.sslverify=false).

For case 1, the answer is mostly "if it hurts, don't do
that". For case 2, we can note that any such example has a
matching inverted surprise (e.g., a user who meant
http.sslverify=true to apply everywhere, but it didn't).

So this whitelist is probably not giving us any benefit, and
is already creating a hassle as people propose things to put
on it. Let's just drop it entirely.

Note that we still need to keep a special code path for
"prepare the submodule environment", because we still have
to take care to pass through $GIT_CONFIG_PARAMETERS (and
block the rest of the repo-specific environment variables).

We can do this easily from within the submodule shell
script, which lets us drop the submodule--helper option
entirely (and it's OK to do so because as a "--" program, it
is entirely a private implementation detail).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/submodule.c b/submodule.c
index c18ab9b..d598881 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1098,50 +1098,13 @@
 	strbuf_release(&rel_path);
 	free((void *)real_work_tree);
 }
-/*
- * Rules to sanitize configuration variables that are Ok to be passed into
- * submodule operations from the parent project using "-c". Should only
- * include keys which are both (a) safe and (b) necessary for proper
- * operation.
- */
-static int submodule_config_ok(const char *var)
-{
-	if (starts_with(var, "credential."))
-		return 1;
-	return 0;
-}
-
-int sanitize_submodule_config(const char *var, const char *value, void *data)
-{
-	struct strbuf *out = data;
-
-	if (submodule_config_ok(var)) {
-		if (out->len)
-			strbuf_addch(out, ' ');
-
-		if (value)
-			sq_quotef(out, "%s=%s", var, value);
-		else
-			sq_quote_buf(out, var);
-	}
-
-	return 0;
-}
 
 void prepare_submodule_repo_env(struct argv_array *out)
 {
 	const char * const *var;
 
 	for (var = local_repo_env; *var; var++) {
-		if (!strcmp(*var, CONFIG_DATA_ENVIRONMENT)) {
-			struct strbuf sanitized_config = STRBUF_INIT;
-			git_config_from_parameters(sanitize_submodule_config,
-						   &sanitized_config);
-			argv_array_pushf(out, "%s=%s", *var, sanitized_config.buf);
-			strbuf_release(&sanitized_config);
-		} else {
+		if (strcmp(*var, CONFIG_DATA_ENVIRONMENT))
 			argv_array_push(out, *var);
-		}
 	}
-
 }