Fix Bitbucket Server import only including first 25 pull requests

The change to paginate repos in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22825 caused the
paginator to stop after 25 pull requests because the limit was set to 25
if none was defined. To fix this, we should only stop if the limit has
actually been set and use the limit parameter to determine the maximum
number of items to process per page.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/55914

changelogs/unreleased/sh-fix-issue-55914.yml

+---
+title: Fix Bitbucket Server import only including first 25 pull requests
+merge_request: 24178
+author:
+type: fixed

lib/bitbucket_server/paginator.rb

@@ -12,7 +12,7 @@ module BitbucketServer
       @url = url
       @page = nil
       @page_offset = page_offset
-      @limit = limit || PAGE_LENGTH
+      @limit = limit
       @total = 0
     end
 
@@ -34,6 +34,8 @@ module BitbucketServer
     attr_reader :connection, :page, :url, :type, :limit
 
     def over_limit?
+      return false unless @limit
+
       @limit.positive? && @total >= @limit
     end
 
@@ -42,11 +44,15 @@ module BitbucketServer
     end
 
     def starting_offset
-      [0, page_offset - 1].max * limit
+      [0, page_offset - 1].max * max_per_page
+    end
+
+    def max_per_page
+      limit || PAGE_LENGTH
     end
 
     def fetch_next_page
-      parsed_response = connection.get(@url, start: next_offset, limit: @limit)
+      parsed_response = connection.get(@url, start: next_offset, limit: max_per_page)
       Page.new(parsed_response, type)
     end
   end

spec/lib/bitbucket_server/paginator_spec.rb

@@ -30,6 +30,17 @@ describe BitbucketServer::Paginator do
       expect { limited.items }.to raise_error(StopIteration)
     end
 
+    it 'does not stop if limit is unspecified' do
+      stub_const("BitbucketServer::Paginator::PAGE_LENGTH", 1)
+      paginator = described_class.new(connection, 'http://more-data', :pull_request, page_offset: 0, limit: nil)
+      allow(paginator).to receive(:fetch_next_page).and_return(first_page, last_page)
+
+      expect(paginator.has_next_page?).to be_truthy
+      expect(paginator.items).to match(['item_1'])
+      expect(paginator.has_next_page?).to be_truthy
+      expect(paginator.items).to match(['item_2'])
+    end
+
     it 'calls the connection with different offsets' do
       expect(connection).to receive(:get).with('http://more-data', start: 0, limit: BitbucketServer::Paginator::PAGE_LENGTH).and_return(page_attrs)