1 files changed, 37 insertions, 3 deletions

diff --git a/setup.c b/setup.c
index 1b120175f2..9107f54a07 100644
--- a/setup.c
+++ b/setup.c
@@ -66,7 +66,14 @@ int check_filename(const char *prefix, const char *arg)
 	const char *name;
 	struct stat st;
 
-	name = prefix ? prefix_filename(prefix, strlen(prefix), arg) : arg;
+	if (!prefixcmp(arg, ":/")) {
+		if (arg[2] == '\0') /* ":/" is root dir, always exists */
+			return 1;
+		name = arg + 2;
+	} else if (prefix)
+		name = prefix_filename(prefix, strlen(prefix), arg);
+	else
+		name = arg;
 	if (!lstat(name, &st))
 		return 1; /* file exists */
 	if (errno == ENOENT || errno == ENOTDIR)
@@ -246,6 +253,25 @@ static const char *prefix_pathspec(const char *prefix, int prefixlen, const char
 		return prefix_path(prefix, prefixlen, copyfrom);
 }
 
+/*
+ * N.B. get_pathspec() is deprecated in favor of the "struct pathspec"
+ * based interface - see pathspec_magic above.
+ *
+ * Arguments:
+ *  - prefix - a path relative to the root of the working tree
+ *  - pathspec - a list of paths underneath the prefix path
+ *
+ * Iterates over pathspec, prepending each path with prefix,
+ * and return the resulting list.
+ *
+ * If pathspec is empty, return a singleton list containing prefix.
+ *
+ * If pathspec and prefix are both empty, return an empty list.
+ *
+ * This is typically used by built-in commands such as add.c, in order
+ * to normalize argv arguments provided to the built-in into a list of
+ * paths to process, all relative to the root of the working tree.
+ */
 const char **get_pathspec(const char *prefix, const char **pathspec)
 {
 	const char *entry = *pathspec;
@@ -497,6 +523,12 @@ static const char *setup_explicit_git_dir(const char *gitdirenv,
 			set_git_work_tree(core_worktree);
 		}
 	}
+	else if (!git_env_bool(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, 1)) {
+		/* #16d */
+		set_git_dir(gitdirenv);
+		free(gitfile);
+		return NULL;
+	}
 	else /* #2, #10 */
 		set_git_work_tree(".");
 
@@ -575,6 +607,8 @@ static const char *setup_bare_git_dir(char *cwd, int offset, int len, int *nongi
 	if (check_repository_format_gently(".", nongit_ok))
 		return NULL;
 
+	setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
+
 	/* --work-tree is set without --git-dir; use discovered one */
 	if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
 		const char *gitdir;
@@ -768,9 +802,9 @@ const char *setup_git_directory_gently(int *nongit_ok)
 
 	prefix = setup_git_directory_gently_1(nongit_ok);
 	if (prefix)
-		setenv("GIT_PREFIX", prefix, 1);
+		setenv(GIT_PREFIX_ENVIRONMENT, prefix, 1);
 	else
-		setenv("GIT_PREFIX", "", 1);
+		setenv(GIT_PREFIX_ENVIRONMENT, "", 1);
 
 	if (startup_info) {
 		startup_info->have_repository = !nongit_ok || !*nongit_ok;