The experiment to add `-no_weak_imports` unconditionally has been a bit
of a failure. It's broken more than it's fixed and I don't think we can
have this as a default for Xcode 8.

Add `ENV.no_weak_imports` to be used by formulae authors and make
`ENV.no_weak_imports a no-op (for now).

We may reconsider this behaviour in future.

Go makes extensive use of weak imports so we need to allow them when
building Go-using software.

Closes https://github.com/Homebrew/homebrew-core/issues/4047.

Also, check in this manpage, adjust the Rakefile and remove the old one.

Fixes #731.

After branching, bumping, pushing, and pr-ing; return to whatever branch
was originally checked out.

In most cases, I'd imagine users to want to continue receiving tap
updates from master. However, after using bump-formula-pr, the tap in
which the formula was bumped is left on the working branch that was
doing the bumping and pull-request. After opening the PR, we should
return to whatever branch the user originally had checked out – most
likely master. (But git allows us to just say "previous branch" by using
`-`)

Without `--no-track`, some git setups may automatically set
`origin/master` as the tracked upstream for the newly created branch.
This upstream is what hub defaults as --head when opening PRs. By not
allowing git to set `origin/master` as upstream, hub can then use the
proper --head for the PR.

Since hub still needs to know what --head is intended to be, we can set
the branch's upstream when pushing: with the --set-upstream option.

Fixes #755

These are intentionally duplicated for now until the Cask migration is
complete.

Closes #746.

Signed-off-by: ilovezfs <ilovezfs@icloud.com>

Reference the revision value so it's more obvious that this does not
refer to e.g. a SCM revision.

Reuse the existing `revision` method that was made more generic.

This will allow it to be used for checking other attributes too.

This allows querying multiple attributes in the same way as
`revision_map` did but without duplicating code or repeatedly traversing
history.

https://github.com/lihaoyi/Ammonite/releases/download/0.7.4/0.7.4

was parsing as "0.7" not "0.7.4" since ".4" was being treated as a
legitimate file extension. At minimum, let's insist that a valid file
extension include at least one letter to avoid lopping off part of the
correct version string.