diff --git a/src/repository/api/ArcanistGitAPI.php b/src/repository/api/ArcanistGitAPI.php
--- a/src/repository/api/ArcanistGitAPI.php
+++ b/src/repository/api/ArcanistGitAPI.php
@@ -497,6 +497,10 @@
       return null;
     }
 
+    if (!strlen($branch)) {
+      return null;
+    }
+
     return $branch;
   }
 
@@ -509,7 +513,7 @@
       // Verify this, and strip it.
       $ref = rtrim($stdout);
       $branch = $this->getBranchNameFromRef($ref);
-      if (!$branch) {
+      if ($branch === null) {
         throw new Exception(
           pht('Failed to parse %s output!', 'git symbolic-ref'));
       }