Failure: https://ci.chromium.org/p/v8/builds/b8950262687537235264

Interestingly, updating an unrelated script referencing this file https://chromium-review.googlesource.com/c/v8/v8/+/845682/85..86/tools/gcmole/run-gcmole.py has helped resolve the failure. This script is only mentioned in the data section of the BUILD.gn file: https://cs.chromium.org/chromium/src/v8/tools/gcmole/BUILD.gn?l=15, so it's unclear why would it be executed during build and furthermore how would it affect the list of files present in the generated isolate file. So it could be a red herring.

Another theory is that https://cs.chromium.org/chromium/src/v8/infra/mb/gn_isolate_map.pyl?l=54 could be somehow related since its type is 'script' even though no script field is present. Could it be picking up the script from the data section of the corresponding BUILD target?