This methods were moved from xdist (ca03269).
Our intention is to keep this code closer to the core, given that it
might break easily due to refactorings.
Having it in the core might also allow to improve the code by moving
some responsibility to the "code" objects (ReprEntry, etc) which
are often found in the reports.
Finally pytest-xdist and pytest-subtests can use those functions
instead of coding it themselves.