parsers: clarify documentation of test-parseindex2.py
This change updates and improves the description of test-parseindex2.py.
In particular, it removes language that can be interpreted to mean that the
test module checks only the C implementation of parsers.parse_index2().
Rather, the module checks parsers.parse_index2(), which can be either the
C or pure Python implementation, depending on which version is being used.
As of e57c532c3835, the module also does more than just compare the return
value with the original Python implementation.
$ hg init
$ echo 0 > a
$ echo 0 > b
$ hg ci -A -m m
adding a
adding b
$ hg rm a
$ hg cat a
0
$ hg cat --decode a # more tests in test-encode
0
$ echo 1 > b
$ hg ci -m m
$ echo 2 > b
$ hg cat -r 0 a
0
$ hg cat -r 0 b
0
$ hg cat -r 1 a
a: no such file in rev 7040230c159c
[1]
$ hg cat -r 1 b
1
Test fileset
$ echo 3 > c
$ hg ci -Am addmore c
$ hg cat 'set:not(b) or a'
3
$ hg cat 'set:c or b'
1
3