test-dumprevlog: fix extra path separator under MacOSX
The "find .hg/store/ -name '*.i'" command returned paths with extra separators
like '.hg/store//00changelog.i'.
Let util.binary check entire data for \0 (
issue1066,
issue1079)
keyword: check for '\0' in entire data before acting
util.binary might not be safe enough, as it fails eg. on certain
pdf files (
issue1066).