Don't import pull request comments from Gitea repos

The Gitea API does not provide the following API endpoint for pull request
comments:

  /api/v1/repos/{owner}/{repo}/pulls/comments

When the importer attempts to request this endpoint it receives a '404
Not Found' error which causes the import to fail. By skipping any
attempts to import pull requests comments from Gitea we can ensure that
the import can complete successfully.

lib/gitlab/legacy_github_import/importer.rb

@@ -55,7 +55,12 @@ module Gitlab
         import_pull_requests
         import_issues
         import_comments(:issues)
+
+        # Gitea doesn't have an API endpoint for pull requests comments
+        unless project.gitea_import?
           import_comments(:pull_requests)
+        end
+
         import_wiki
 
         # Gitea doesn't have a Release API yet

spec/lib/gitlab/legacy_github_import/importer_spec.rb

@@ -24,7 +24,13 @@ describe Gitlab::LegacyGithubImport::Importer do
         end
 
         expect(importer).to receive(:import_comments).with(:issues)
+
+        if expected_not_called.include? :import_comments_pull_requests
+          expect(importer).not_to receive(:import_comments).with(:pull_requests)
+          expected_not_called.delete_at expected_not_called.index :import_comments_pull_requests
+        else
           expect(importer).to receive(:import_comments).with(:pull_requests)
+        end
 
         expected_not_called.each do |method_name|
           expect(importer).not_to receive(method_name)
@@ -289,7 +295,7 @@ describe Gitlab::LegacyGithubImport::Importer do
     end
 
     it_behaves_like 'Gitlab::LegacyGithubImport::Importer#execute' do
-      let(:expected_not_called) { [:import_releases] }
+      let(:expected_not_called) { [:import_releases, :import_comments_pull_requests] }
     end
     it_behaves_like 'Gitlab::LegacyGithubImport::Importer#execute an error occurs'
     it_behaves_like 'Gitlab::LegacyGithubImport unit-testing'