Matthieu Moy [off-list ref] writes:
Implementing "git rm -u" as a tree-wide command would create a
discrepancy with "git add -u". Implementing it as a "current directory"
command would make the migration harder if we eventually try to change
"git add -u". Perhaps "git rm -u" should be forbidden from a
subdirectory (with an error message pointing to "git rm -u :/" and "git
rm -u ."), waiting for a possible "git add -u" change.
Yeah, that sounds sensible. Start with a "'git rm -u' is forbidden
without arguments", give advise to use either "." or ":/". And stop
there.
The first step of "git add -u" migration plan would be to warn when
no argument is given and update all the existing index entries, and
give the same advise to use either "." or ":/". Keep this for three
cycles: 3 * (8 to 10 weeks per cycle) = 27 weeks ~ 1/2 year.
The second step would be to forbid "git add -u", and keep the
advise. That will make it in-line with "git rm -u".