mingw: respect core.hidedotfiles = false in git-init again

This is a brown paper bag. When adding the tests, we actually failed
to verify that the config variable is heeded in git-init at all. And
when changing the original patch that marked the .git/ directory as
hidden after reading the config, it was lost on this developer that
the new code would use the hide_dotfiles variable before the config
was read.

The fix is obvious: read the (limited, pre-init) config *before*
creating the .git/ directory.

This fixes https://github.com/git-for-windows/git/issues/789

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

builtin/init-db.c

@@ -155,6 +155,9 @@ static int git_init_db_config(const char *k, const char *v, void *cb)
 	if (!strcmp(k, "init.templatedir"))
 		return git_config_pathname(&init_db_template_dir, k, v);
 
+	if (starts_with(k, "core."))
+		return platform_core_config(k, v, cb);
+
 	return 0;
 }
 
@@ -361,6 +364,9 @@ int init_db(const char *git_dir, const char *real_git_dir,
 	}
 	startup_info->have_repository = 1;
 
+	/* Just look for `init.templatedir` and `core.hidedotfiles` */
+	git_config(git_init_db_config, NULL);
+
 	safe_create_dir(git_dir, 0);
 
 	init_is_bare_repository = is_bare_repository();

t/t0001-init.sh

@@ -453,6 +453,18 @@ test_expect_success 're-init from a linked worktree' '
 	)
 '
 
+test_expect_success MINGW 'core.hidedotfiles = false' '
+	git config --global core.hidedotfiles false &&
+	rm -rf newdir &&
+	(
+		sane_unset GIT_DIR GIT_WORK_TREE GIT_CONFIG &&
+		mkdir newdir &&
+		cd newdir &&
+		git init
+	) &&
+	! is_hidden newdir/.git
+'
+
 test_expect_success MINGW 'redirect std handles' '
 	GIT_REDIRECT_STDOUT=output.txt git rev-parse --git-dir &&
 	test .git = "$(cat output.txt)" &&