Two years later, I get the exact same failure in both repository 3.3.2+ and installed 3.3.2. So eol extension and .hgignore seem irrelevant.

I sometime think Python should stop generating files with \r\n. In other words, change os.linesep to '\n' even on windows. Or maybe just do it for test files that will be read in binary mode and compared with generated data. The only program I know of that does not recognize \n alone is Notepad, and that hardly worth bothering with.

Repository 3.4.0a1+ has the same error + essentially the same in
test_as_bytes. (Repository 2.7.5+ passes.) For one test, \r only appears in the file; in the other, it also sporadically appeared in the generated bytes. I don't know why the test works on buildbots, but the attached patch fixes it for my desktop. Any objections to committing it?