This started happening as a result of bbc167b, which avoids reloading
previously defined formulae. The exception alters its message if the
name parameter appears to be a tapped formula, but this is lost if we
only pass in the "stem" of the pathname.
Long-term this probably needs some restructuring, perhaps with a
separate exception for tapped formula, but for now this should re-enable
the more useful error message.
FixesHomebrew/homebrew#15374.
Signed-off-by: Jack Nagel <jacknagel@gmail.com>
35c47f81f2