FIX: make branch hunting backwards compatible

FIX: make branch hunting backwards compatible

Previous to this change older versions of Discourse would fail here

diff --git a/lib/docker_manager/git_repo.rb b/lib/docker_manager/git_repo.rb
index e425eba..5581158 100644
--- a/lib/docker_manager/git_repo.rb
+++ b/lib/docker_manager/git_repo.rb
@@ -113,7 +113,11 @@ class DockerManager::GitRepo
   end
 
   def tracking_branch
-    Discourse.find_compatible_git_resource(path) || run("for-each-ref --format='%(upstream:short)' $(git symbolic-ref -q HEAD)")
+    branch = nil
+    if defined?(Discourse.find_compatible_git_resource)
+      branch = Discourse.find_compatible_git_resource(path)
+    end
+    branch || run("for-each-ref --format='%(upstream:short)' $(git symbolic-ref -q HEAD)")
   end
 
   def run(cmd)

GitHub sha: a9df2937

Ty I think this fixed my problem