Mongot variants have special tarballs, which means that they shouldn't be overwritten by other tasks. In order to do this, we name the compile_variant field with something unique to the variant, e.g. 8.0, master. However, the x86 variant in 8.0 shares the compile_variant name with other tasks, see here. This causes a fluke BF where the tarball gets replaced between setting up the suite and actually running the test, the latter which won't be able to find the mongot binary and fail, see BF-38454.

As linked above, master works fine so this is an 8.0 change only rather than a backport.