Passing Formula.factory the name of a keg that belongs to a non-core
formula will cause an error to be raised; we don't really care, so just
fake a totally empty install receipt in this case.
Signed-off-by: Jack Nagel <jacknagel@gmail.com>
This will be useful in places where we need information about things
other than the currently linked keg, such as `brew info`.
Signed-off-by: Jack Nagel <jacknagel@gmail.com>
FormulaInstaller now loads the install recipt of a previous install and appends
the `used_options` to ARGV before forking to build. This means `brew upgrade`
will "remember" which options were invoked for the last install and re-use
them.
FixesHomebrew/homebrew#5250.
