allow using the 'a' flag as a mode for opening a GzipFile. gzip
files, surprisingly enough, can be concatenated and then decompressed;
the effect is to concatenate the two chunks of data.
If we support it on writing, it should also be supported on reading.
This *wasn't* trivial, and required rearranging the code in the
reading path, particularly the _read() method.
Raise IOError instead of RuntimeError in two cases, 'Not a gzipped file'
and 'Unknown compression method'
problem was a couple of bugs in the readline implementation.
1. Include the '\n' in the string returned by readline
2. Bug calculating new buffer size in _unread
Also remove unncessary import of StringIO
Here's my suggested replacement for gzip.py for 1.5.1. I've
re-implemeted methods readline and readlines, added an _unread, and
tweaked read and _read.
I tried a more complicated buffer scheme for unread (using a list of
strings and string.join), but it was more complicated and slower.
This version is a lot faster than the current version and is still
pretty simple.
Andrew M. Kuchling
Jeremy Hylton
Guido van Rossum