remotefilelog: actually fix (and test this time) a bytes vs str issue I attempted this in 94670e124d29 but we didn't actually have any tests for this function it seems, and I mistook "it works now" for it being fixed (when what had actually happened was that my cache had populated enough that I didn't trigger the minimum threshold on my reattempts). Differential Revision: https://phab.mercurial-scm.org/D7785