The "upgrades with asking for user prompts with dependants checks"
test for `cmd/upgrade` has been failing on CI. The regex in the test
doesn't match expected output because the negative lookaheads aren't
working as expected. The intention is to make sure that the names
aren't repeated (i.e., second shouldn't match first, third shouldn't
match first or second) but the negative lookaheads should be
_inside_ the second/third capture group for this to work as intended.
This updated regex should work as expected. I manually tested it
using the output from CI to make sure that it matches when no formula
names are repeated (e.g., `Formulae (3): testball, testball4,
testball5`) and does not match if formula names are repeated (e.g.,
`Formulae (3): testball5, testball4, testball5`).
After upgrading existing kegs, we now search and upgrade their
dependents as well. If any are detected that have broken linkage, they
are reinstalled from source.
If there are any formulae in the dependents tree that are pinned, they
are only reinstalled if they're not outdated; in all cases, a suitable
message is printed detailing the kegs that will be acted upon.
