FogBugz import fails when encountering "entity expansion has grown too large" error for cases exceeding entity size limit

GitLab Version: CE 8.16.6

Our user try to migrate data from Fogbugz with the help of import_projects_from_fogbugz. The import ended in status=failed.

We checked logs but could not find anything obvious. No connection issue, no authentication issue. The import seems finished user_map step, but then started logging a lot of such entries in gitlab-workhorse.log:

code.example.com [::1]:39198 - - [2017-03-21 23:08:26.126829987 +0000 UTC] "GET /import/fogbugz/jobs HTTP/1.1" 304 0 "https://code.example.com/username/X_PROJECT/wikis/home" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/56.0.2924.76 Chrome/56.0.2924.76 Safari/537.36" 0.046135
code.example.com 127.0.0.1:57556 - - [2017-03-21 23:08:30.122449308 +0000 UTC] "GET /import/fogbugz/jobs HTTP/1.1" 304 0 "https://code.example.com/username/X_PROJECT/wikis/home" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/56.0.2924.76 Chrome/56.0.2924.76 Safari/537.36" 0.068606
code.example.com [::1]:39216 - - [2017-03-21 23:08:34.120718077 +0000 UTC] "GET /import/fogbugz/jobs HTTP/1.1" 304 0 "https://code.example.com/username/X_PROJECT/wikis/home" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/56.0.2924.76 Chrome/56.0.2924.76 Safari/537.36" 0.047024
...

That GET... wiki/home line just goes on and on until the migration exited with status=failed shown on GitLab console. We searched production logs and unicorn logs. Did not find anything useful for further debugging.

Any ideas what might have been wrong?