If you use recompressxml in the mwbzutils package, as of version 0.0.9
(just deployed) it no longer writes bz2 compressed data by default to
stdout; instead it relies on the extension of the output file and will
write either gzipped, bz2 or plain text output, accordingly. This means
that if it is directed to write to stdout, this will be uncompressed data.
You can work around this in your scripts by piping the text from stdout to
bzip directly from recompressxml.
This change came as part of some speedup work. I won't discuss that more
until we see how the next couple of runs go.
Thanks for your understanding.
Ariel