These command fails on my machine:

./mach raptor --test raptor-tp6-amazon-firefox --verbose
...
19:43:10    FATAL - Can't find the virtualenv module
19:43:10    FATAL - Running post_fatal callback...
19:43:10    FATAL - Exiting -1

I tracked it down to a regression from Bug 1408051. Looks like {abs_src_dir} is not defined in my build: https://searchfox.org/mozilla-central/rev/828f2319c0195d7f561ed35533aef6fe183e68e3/testing/mozharness/mozharness/base/python.py#365-378

From what I could understand is that the abs_src_dir key is not set here(https://searchfox.org/mozilla-central/source/testing/mozharness/mozharness/mozilla/testing/raptor.py#446-455) that's why the command is failing because it's not able to find the virtualenv module due to a KeyError

I think this might work but it would be great if :ahal could also take a look at it

The fix in comment 2 looks reasonable to me. Hamzah, were you able to reproduce and confirm the fix works? Mind pushing a revision to phabricator? Thanks for looking into it!

Yeah, I was able to reproduce it on running the raptor command provided. The fix worked for me on mac, I even tested it on windows.

Backed out for mass failures on python.py

Backout link: https://hg.mozilla.org/integration/autoland/rev/3077c06189677d30a3e4e066dea97f2e083c6501
Log link: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=311200380&repo=autoland&lineNumber=806

Set release status flags based on info from the regressing bug 1408051

:kimberlythegeek can you run raptor on your mac system?

I can confirm that I don't hit this issue on Linux anymore (I hit the same issue on that platform).

Tested on MacOS 10.15.6 and did not experience any issues

Great, so it's working now. Closing this bug.