Fix Mercurial tests

Dependencies

• [2] NQPGIRXX Revert "hydra-eval-jobs -> nix eval-hydra-jobs"
• [*] G2ZB6464 first test, not yet in buildprocess
• [*] LAJHRL6O Fix tests

Change contents

• edit in tests/Makefile.am at line 17
  [5.213]

  [2.10106]
  + PYTHONPATH= \