py3: don't double-convert "opts" to bytes The "opts" are already converted to bytes at the beginning of the function. Doing it twice results in a crash, which makes test-uncommit.t fail. The extra call was added recently, in ff1ff2aae132 (uncommit: add support to modify the commit message and date, 2019-09-07). test-uncommit.t passes again after this patch. Differential Revision: https://phab.mercurial-scm.org/D6864