Fix tests when JULIA_DEPOT_PATH is set

[Keno]

When JULIA_DEPOT_PATH is set, the stdlib depots might not be in DEPOT_PATH. However, because the test does not inherit the env var and instead sets it to something custom, the child processes will get the default. To make sure the tests work properly, just reach into base and query the right values.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.34%. Comparing base (661112e) to head (a80a88b).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #154      +/-   ##
==========================================
- Coverage   79.38%   79.34%   -0.05%     
==========================================
  Files          10       10              
  Lines        1955     1951       -4     
==========================================
- Hits         1552     1548       -4     
  Misses        403      403              

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[JamesWrigley]

Not sure I follow how this could break, are you saying that if JULIA_DEPOT_PATH is set to something that doesn't include the stdlib depots before ] test is run then the test process running test/distributed_exec.jl will not see the stdlib depots at all and thus cause the tests to fail?

[Keno]

Yes

[JamesWrigley]

LGTM!