init: do parse _all_ core.* settings early

In Git for Windows, `has_symlinks` is set to 0 by default. Therefore, we
need to parse the config setting `core.symlinks` to know if it has been
set to `true`. In `git init`, we must do that before copying the
templates because they might contain symbolic links.

Even if the support for symbolic links on Windows has not made it to
upstream Git yet, we really should make sure that all the `core.*`
settings are parsed before proceeding, as they might very well change
the behavior of `git init` in a way the user intended.

This fixes #3414

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

config.c

@@ -1387,8 +1387,8 @@ int git_config_color(char *dest, const char *var, const char *value)
 	return 0;
 }
 
-static int git_default_core_config(const char *var, const char *value,
-				   const struct config_context *ctx, void *cb)
+int git_default_core_config(const char *var, const char *value,
+			    const struct config_context *ctx, void *cb)
 {
 	/* This needs a better name */
 	if (!strcmp(var, "core.filemode")) {

config.h

@@ -167,6 +167,8 @@ typedef int (*config_fn_t)(const char *, const char *,
 
 int git_default_config(const char *, const char *,
 		       const struct config_context *, void *);
+int git_default_core_config(const char *var, const char *value,
+			    const struct config_context *ctx, void *cb);
 
 /**
  * Read a specific file in git-config format.

setup.c

@@ -2411,7 +2411,7 @@ int init_db(const char *git_dir, const char *real_git_dir,
 	 * have set up the repository format such that we can evaluate
 	 * includeIf conditions correctly in the case of re-initialization.
 	 */
-	git_config(platform_core_config, NULL);
+	git_config(git_default_core_config, NULL);
 
 	safe_create_dir(git_dir, 0);