Reproduce:
amsa@amsa-Latitude-7480:~$ git clone --depth 1 https://phabricator.wikimedia.org/source/tool-quickstatements.git Cloning into 'tool-quickstatements'... error: RPC failed; HTTP 500 curl 22 The requested URL returned error: 500 Internal Server Error fatal: The remote end hung up unexpectedly
git clone https://phabricator.wikimedia.org/source/tool-quickstatements.git works fine. The URL is advertised in https://toolsadmin.wikimedia.org/tools/id/quickstatements/repos/id/tool-quickstatements and https://phabricator.wikimedia.org/source/tool-quickstatements/
It causes failures in Wikibase docker images: https://travis-ci.org/wmde/wikibase-docker/jobs/625702926?utm_medium=notification&utm_source=github_status