baseset: implement a fastasc and fastdesc
Baseset contains already-computed revisions. It is considered "cheap" to do
operations on an already-computed set. So we add attributes to hold version of
the list in ascending and descending order and use them for `fastasc` and
`fastdesc`. Having distinct lists is important to provide correct iteration in
all cases. Altering a python list will impact an iterator connected to it.
eg: not preserving order at iterator creation time
>>> l = [0, 1]
>>> i = iter(l)
>>> l.reverse()
>>> list(i)
[1, 0]
eg: corrupting in progress iteration
>>> l = [0, 1]
>>> i = iter(l)
>>> i.next()
0
>>> l.reverse()
>>> i.next()
0
syntax: glob
*.elc
*.tmp
*.orig
*.rej
*~
*.mergebackup
*.o
*.so
*.dll
*.exe
*.pyd
*.pyc
*.pyo
*$py.class
*.swp
*.prof
*.zip
\#*\#
.\#*
tests/.coverage*
tests/annotated
tests/*.err
tests/htmlcov
build
contrib/hgsh/hgsh
contrib/vagrant/.vagrant
dist
packages
doc/common.txt
doc/*.[0-9]
doc/*.[0-9].txt
doc/*.[0-9].gendoc.txt
doc/*.[0-9].{x,ht}ml
MANIFEST
MANIFEST.in
patches
mercurial/__version__.py
mercurial/hgpythonlib.h
mercurial.egg-info
.DS_Store
tags
cscope.*
i18n/hg.pot
locale/*/LC_MESSAGES/hg.mo
hgext/__index__.py
# files installed with a local --pure build
mercurial/base85.py
mercurial/bdiff.py
mercurial/diffhelpers.py
mercurial/mpatch.py
mercurial/osutil.py
mercurial/parsers.py
syntax: regexp
^\.pc/
^\.(pydev)?project
# hackable windows distribution additions
^hg-python
^hg.py$