Additionally include our bootstrap code in `brew.sh`, Bash utilities in
`utils.sh` and `utils/*.sh`, `superenv` shims, and the Bash completion.

Closes #654.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

e.g. Caskroom/homebrew-cask.

Thanks to UniqMartin for the fix.

Fixes #655.

Doesn't feel like a good reason to abort installation for users if the
formula author has specified a conflict that doesn't exist. Instead,
behave more like the `TapFormulaUnavailableError` but print a message
telling people to report to the formula authors.

Closes https://github.com/Homebrew/homebrew-versions/issues/1327

This reverts commit 24f7e671.

Closes #648.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

Closes #584.

Signed-off-by: Xu Cheng <xucheng@me.com>

Introduce `--fetch-HEAD` option. Without this option upgrade and
outdated never fetch latest upstream commit to detect if HEAD is
outdated -- tabs are used instead. However, if option is passed,
we fetch commit from upstream, which is more time consuming,
but we can be sure that version is up-to-date or outdated.

* add `latest_head_version` to return latest HEAD version installed
* add `latest_head_prefix` to return Pathname with latest HEAD version
* add `head_version_outdated?` to check if HEAD version is up-to-date

If we try to call `Formulary.from_keg(f, :head)` on the keg that
is not HEAD-keg itself, we don't need to update commit of
returned formula and should use just HEAD version with nil commit.

Same is true for `ARGV.resolved_formulae`