This was worded in a confusing way, and made an assumption about future
OS X versions that we don't know to be true.

Also, it's probably wrong to state that the CLT location is dependent on
the OS X version; surely there will be a newer CLT for 10.8 that gets
installed in the same location as on 10.9. But we don't know any better
yet.

I'm tired of not remembering if start_with?/end_with? are portable, so
just add them both if they're not defined.

It is supposed to accept a variable number of prefixes, and also to
check if they are convertible to strings. This matches behavior
documented in RubySpec.

This has been tested with several dozen formulae without any
superenv-related issues.

some links like example.com were not clickable
in some markdown viewers.

This check was only occurring in one branch of the conditional.
As a result, if you ran `brew upgrade` with no args and there were no packages to upgrade,
the nonsensical message

"==> Upgrading 0 outdated package, with result:"

would be printed.

Closes Homebrew/homebrew#21316.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

This is needed for local bottle installation and also possible when
detecting bottle versions from URLs.

Needs a less hacky fix but at least this will stop failing tests.

In 10.9 we'll probably have to use that code path
anyways and by now we have adapted all formulae
to be able to build on Xcode-only.