perf: make perf.run-limits code work with Python 3 We need b'' because perf.py isn't run through the source transformer. We need to cast the exception to bytes using pycompat.bytestr() because ValueError can't be %s formatted due to built-in exceptions lacking __bytes__. We need to pycompat.sysstr() before the float() and int() cast so the ValueError message doesn't have b'' in it. Even with that, it looks like the error message for the ValueError for float casts added quotes, so we need to account for that in test output. Differential Revision: https://phab.mercurial-scm.org/D6200