help: add a mechanism to change flags' help depending on config
It seems reasonable to have a similar mechanism for the rest of the
help, but no such thing is implemented.
The goal is to make the help of commands clearer in the presence of
significant default changes, like tweakdefaults or with company-wide
hgrcs. In these cases, a user looking at the help of a command doesn't
exactly know what his hgrc is doing.
Apply to this to the --git option of commands that display diffs, as
this option in particular causes confusion for some reason.
Differential Revision: https://phab.mercurial-scm.org/D8100
$ hg init
$ echo 123 > a
$ hg add a
$ hg commit -m "first" a
$ mkdir sub
$ echo 321 > sub/b
$ hg add sub/b
$ hg commit -m "second" sub/b
$ cat sub/b
321
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cat sub/b 2>/dev/null || echo "sub/b not present"
sub/b not present
$ test -d sub || echo "sub not present"
sub not present