probably need more tests here

A few that come to mind:

# throws
archive.writestr("C:\just\say\no\to\winpaths", "this is weird")  [ in theory, we could translate to posix paths, but I'd consider that a sign of bogus manifest for now]

# should throw exception
archive.writestr("\\nethost\share\whatever", "we dont support UNC paths either")

# should be okay
archive.writestr("./some/path", "this is okay I think, though odd")