Merge branch 'maint'

* maint:
  git-prune-packed.txt: fix reference to GIT_OBJECT_DIRECTORY
  clone --branch: refuse to clone if upstream repo is empty

Author: gitster

Documentation/git-prune-packed.txt

@@ -14,7 +14,7 @@ SYNOPSIS
 
 DESCRIPTION
 -----------
-This program searches the `$GIT_OBJECT_DIR` for all objects that currently
+This program searches the `$GIT_OBJECT_DIRECTORY` for all objects that currently
 exist in a pack file as well as the independent object directories.
 
 All such extra objects are removed.

builtin/clone.c

@@ -945,6 +945,10 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 			our_head_points_at = remote_head_points_at;
 	}
 	else {
+		if (option_branch)
+			die(_("Remote branch %s not found in upstream %s"),
+					option_branch, option_origin);
+
 		warning(_("You appear to have cloned an empty repository."));
 		mapped_refs = NULL;
 		our_head_points_at = NULL;

t/t5706-clone-branch.sh

@@ -20,7 +20,9 @@ test_expect_success 'setup' '
 	 echo one >file && git add file && git commit -m one &&
 	 git checkout -b two &&
 	 echo two >file && git add file && git commit -m two &&
-	 git checkout master)
+	 git checkout master) &&
+	mkdir empty &&
+	(cd empty && git init)
 '
 
 test_expect_success 'vanilla clone chooses HEAD' '
@@ -61,4 +63,8 @@ test_expect_success 'clone -b with bogus branch' '
 	test_must_fail git clone -b bogus parent clone-bogus
 '
 
+test_expect_success 'clone -b not allowed with empty repos' '
+	test_must_fail git clone -b branch empty clone-branch-empty
+'
+
 test_done