Force to recreate all diffs on import

If for whatever reason we fail to import MR data,
subsequent run will fail as we try to insert duplicate data.
Instead of trying to recover, lets delete all and retry again.

1 files changed, 6 insertions, 10 deletions

diff --git a/lib/gitlab/import/merge_request_helpers.rb b/lib/gitlab/import/merge_request_helpers.rb
index fa3ff6c3f12..b3fe1fc0685 100644
--- a/lib/gitlab/import/merge_request_helpers.rb
+++ b/lib/gitlab/import/merge_request_helpers.rb
@@ -38,7 +38,6 @@ module Gitlab
       end
       # rubocop: enable CodeReuse/ActiveRecord
 
-      # rubocop: disable CodeReuse/ActiveRecord
       def insert_or_replace_git_data(merge_request, source_branch_sha, target_branch_sha, already_exists = false)
         # These fields are set so we can create the correct merge request
         # diffs.
@@ -47,24 +46,21 @@ module Gitlab
 
         merge_request.keep_around_commit
 
+        # We force to recreate all diffs to replace all existing data
+        # We use `.all` as otherwise `dependent: :nullify` (the default)
+        # takes an effect
+        merge_request.merge_request_diffs.all.delete_all if already_exists
+
         # MR diffs normally use an "after_save" hook to pull data from Git.
         # All of this happens in the transaction started by calling
         # create/save/etc. This in turn can lead to these transactions being
         # held open for much longer than necessary. To work around this we
         # first save the diff, then populate it.
-        diff =
-          if already_exists
-            merge_request.merge_request_diffs.take ||
-              merge_request.merge_request_diffs.build
-          else
-            merge_request.merge_request_diffs.build
-          end
-
+        diff = merge_request.merge_request_diffs.build
         diff.importing = true
         diff.save
         diff.save_git_content
       end
-      # rubocop: enable CodeReuse/ActiveRecord
     end
   end
 end