Fix installation to preserve one-file project.

3 jobs for master in 34 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Lint
passed #270911
docker
lint

00:00:17

 
  Test
passed #270912
docker
unittests_py2

00:00:16

passed #270913
docker
unittests_py3

00:00:17