This reverts commit 862c3ba4.

audit: handle a nil revision map.

Deprecate 32-bit options.

Remove Xcode prerelease warnings.

These were formerly supported but as it has been a very long time since
32-bit software was necessary on macOS these have been deprecated with
a `brew audit` warning and a future `odeprecated`.

update-reset: add new command.

postinstall: don't allow writes to prefix itself.

super/cc: loosen cellar formula regex.

At this point we probably do want to know about issues that crop up in
betas so we can fix them before the new version of Xcode is released.
Additionally, this doesn't really work well any more with our new
tag-based workflow as it means we need to cut a new tag immediately
after a new Xcode is released.

audit: don't allow use of OS.mac?/OS.linux?.

Never trigger too old CLT check on <10.7.

While we fake a CLT for these versions they never shipped with the CLT
so cannot update it.

Forbid their use in Homebrew/core which only supports macOS. This may
be added to more/all official taps in future.

Add new `brew update-reset` command to provide a helpful troubleshooting
fallback to fetch and reset all repositories. This could have lived in
`brew update` but it makes sense to avoid the complexity of sharing
logic between these scripts and keeping this one simpler.

create: handle Version::NULL correctly.

Fixes #1688.

diagnostic: check for multiple Cellars.

audit: flag use of "fails_with :llvm".

prune: don't remove top-level directories.

which_all: don't assume path is a string.

Tweak issue template and contributing guidelines.

Fix error message when cask fails to install.

fix typo

Match HOMEBREW_TAP_FORMULA_REGEX to avoid skipping valid cellar regexes.

formulary: call tap not formula

Fixes #1668

Revert "formula: runtime deps of build deps aren't runtime"

Fix typo

XCode 8.2 is stable

Also, add TODOs for deprecating this properly at a later point.

Even if they're empty we want to keep these top-level directories around
as the installer has nicely created them with the correct permissions
and this avoids potentially having to use `sudo` to recreate them.

- Note issues may be closed without comment if sufficient information is
  not provided.
- Deprecate Homebrew/brew-evolution, note new feature request flow
- Note some issues should be created on Homebrew/brew

And tell people to delete the HOMEBREW_REPOSITORY one. The
HOMEBREW_PREFIX one is preferable for bottling.

Only the top-level directories inside it. We don't want formulae writing
random junk in e.g. `/usr/local` even in `postinstall`.