We need b'' because perf.py isn't run through the source
We need to cast the exception to bytes using pycompat.bytestr()
because ValueError can't be %s formatted due to built-in exceptions
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