Don't show conflicts when there are none

app/models/merge_request.rb

@@ -777,7 +777,11 @@ class MergeRequest < ActiveRecord::Base
     return @conflicts_can_be_resolved_in_ui = false unless has_complete_diff_refs?
 
     begin
-      @conflicts_can_be_resolved_in_ui = conflicts.files.each(&:lines)
+      # Try to parse each conflict. If the MR's mergeable status hasn't been updated,
+      # ensure that we don't say there are conflicts to resolve when there are no conflict
+      # files.
+      conflicts.files.each(&:lines)
+      @conflicts_can_be_resolved_in_ui = conflicts.files.length > 0
     rescue Rugged::OdbError, Gitlab::Conflict::Parser::ParserError, Gitlab::Conflict::FileCollection::ConflictSideMissing
       @conflicts_can_be_resolved_in_ui = false
     end

spec/models/merge_request_spec.rb

@@ -890,6 +890,12 @@ describe MergeRequest, models: true do
       expect(merge_request.conflicts_can_be_resolved_in_ui?).to be_falsey
     end
 
+    it 'returns a falsey value when the MR is marked as having conflicts, but has none' do
+      merge_request = create_merge_request('master')
+
+      expect(merge_request.conflicts_can_be_resolved_in_ui?).to be_falsey
+    end
+
     it 'returns a falsey value when the MR has a missing ref after a force push' do
       merge_request = create_merge_request('conflict-resolvable')
       allow(merge_request.conflicts).to receive(:merge_index).and_raise(Rugged::OdbError)