"Exception: Xvfb mmap file did not appear" when running multiple tests when a Xvfb already exists

[dosaki]

This issue is being raised in xvfb.py:79

If I already have a Xvfb screen up on say :10, then your code fails when it reaches a test that would spin up a screen on :10

The workaround is changing the existing virtual screen to something higher like :999.

Could the code not poll to see if an Xvfb display was already taken?