read_ali_ark crashes when reading gzipped file

[Serhiy-Shekhovtsov]

I am trying to read the alignment file using read_ali_ark method. My code looks like this:

src_file = 's5/exp/tri2_ali/ali.1.gz'
abc = kaldi_io.read_ali_ark(src_file)

But this crashes on assert. It goes like this:

• read_ali_ark will call open_or_fd method.
• It will read the file using gzip library.
• This library will set fd.mode property to an integer.
• But then the code will try to assert that fd.mode is a string and contains 'b'.

Simply removing this assert fixes the issue and makes it possible to read gzipped ark files.