stat-cache break on long file names

[Johan Rydberg]

The stat-cache does not support very long filenames.  Example:

$ bzr init
$ touch this_is_a_very_long_file_name_is_it_not_or_what_do_you_think_1234567890
$ bzr add this_is_a_very_long_file_name_is_it_not_or_what_do_you_think_1234567890
$ bzr status
added:
  this_is_a_very_long_file_name_is_it_not_or_what_do_you_think_1234567890
$ bzr status
bzr: list index out of range
  at /home/jrydberg/src/bzr.dev/bzrlib/statcache.py:163 in load_cache()
  see ~/.bzr.log for debug information

This seem to be because the b2a_qp function break very long lines.
I'm sorry for the long line here, but I guess you get the picture:

$ cat .bzr/stat-cache
### bzr statcache v2
this_is_a_very_long_file_name_is_it_not_or_what_do_you_think_1234567890-200=
50519233537-d73a34e7d88975d9 da39a3ee5e6b4b0d3255bfef95601890afd80709 this_is_a_very_long_file_name_is_it_not_or_what_do_you_think_1234567890 0 1116545730 1116545730 189702 772


~j