cherokee: depends on wget if HEAD

Closes #20196.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
Require hardware where it is needed
test_mach: move helper method out of global namespace
Requirement: fix typo
Refactor Requirement.expand
Allow explicit conversion of requirements to deps
Revert "Remove default_formula from MPIDependency."

This reverts commit 9aaa89dbe832387249ab3ea4e22a8018cc9fe30a.
PostgresqlDependency: use canonical name for default formula