[GitRepository] #clone_repo_if_missing with #git_transaction

Changed `#clone_repo` to `#clone_repo_if_missing`, and encapsulated the
logic that existed in `#worktree` (dir check) in it as well.

Also wrapped the method in a `#git_transaction`, which makes sure only
one process handles this at a time.

Author: NickLaMuro

app/models/git_repository.rb

@@ -156,7 +156,7 @@ def refresh_tags
 
   def worktree
     @worktree ||= begin
-      clone_repo unless Dir.exist?(directory_name)
+      clone_repo_if_missing
       fetch_worktree
     end
   end
@@ -165,13 +165,15 @@ def fetch_worktree
     GitWorktree.new(worktree_params)
   end
 
-  def clone_repo
-    handling_worktree_errors do
-      message = "Cloning #{url} to #{directory_name}..."
-      _log.info(message)
-      GitWorktree.new(worktree_params.merge(:clone => true, :url => url))
-      @updated_repo = true
-      _log.info("#{message}...Complete")
+  def clone_repo_if_missing
+    git_transaction do
+      handling_worktree_errors do
+        message = "Cloning #{url} to #{directory_name}..."
+        _log.info(message)
+        GitWorktree.new(worktree_params.merge(:clone => true, :url => url))
+        @updated_repo = true
+        _log.info("#{message}...Complete")
+      end unless Dir.exist?(directory_name)
     end
   end
 

spec/models/git_repository_spec.rb

@@ -97,7 +97,7 @@
         tag_info_hash[name]
       end
 
-      expect(repo).to receive(:clone_repo).once.with(no_args).and_call_original
+      expect(repo).to receive(:clone_repo_if_missing).once.with(no_args).and_call_original
       expect(GitWorktree).to receive(:new).with(anything).and_return(gwt)
       expect(gwt).to receive(:fetch_and_merge).with(no_args)