Remove FormulaAlreadyInstalledError

install is the only command that can trigger this warning, so it should
be handled before instantiating the installer.

Library/Homebrew/cmd/install.rb

@@ -25,6 +25,8 @@ module Homebrew
     end unless ARGV.force?
 
     begin
+      formulae = []
+
       ARGV.formulae.each do |f|
         # Building head-only without --HEAD is an error
         if not ARGV.build_head? and f.stable.nil?
@@ -38,11 +40,19 @@ module Homebrew
         if ARGV.build_head? and f.head.nil?
           raise "No head is defined for #{f.name}"
         end
+
+        if f.installed?
+          msg = "#{f.name}-#{f.installed_version} already installed"
+          msg << ", it's just not linked" unless f.linked_keg.symlink? or f.keg_only?
+          opoo msg
+        else
+          formulae << f
+        end
       end
 
       perform_preinstall_checks
 
-      ARGV.formulae.each { |f| install_formula(f) }
+      formulae.each { |f| install_formula(f) }
     rescue FormulaUnavailableError => e
       ofail e.message
       query = query_regexp(e.name)
@@ -126,8 +136,6 @@ module Homebrew
   rescue FormulaInstallationAlreadyAttemptedError
     # We already attempted to install f as part of the dependency tree of
     # another formula. In that case, don't generate an error, just move on.
-  rescue FormulaAlreadyInstalledError => e
-    opoo e.message
   rescue CannotInstallFormulaError => e
     ofail e.message
     check_macports

Library/Homebrew/cmd/reinstall.rb

@@ -31,8 +31,6 @@ module Homebrew
     fi.finish
   rescue FormulaInstallationAlreadyAttemptedError
     # next
-  rescue FormulaAlreadyInstalledError => e
-    opoo e.message
   rescue Exception
     ignore_interrupts { restore_backup(keg, f) }
     raise

Library/Homebrew/exceptions.rb

@@ -81,8 +81,6 @@ end
 
 class CannotInstallFormulaError < RuntimeError; end
 
-class FormulaAlreadyInstalledError < RuntimeError; end
-
 class FormulaInstallationAlreadyAttemptedError < RuntimeError
   def initialize(formula)
     super "Formula installation already attempted: #{formula.name}"

Library/Homebrew/formula_installer.rb

@@ -104,12 +104,6 @@ class FormulaInstaller
   def check_install_sanity
     raise FormulaInstallationAlreadyAttemptedError, formula if @@attempted.include?(formula)
 
-    if formula.installed?
-      msg = "#{formula.name}-#{formula.installed_version} already installed"
-      msg << ", it's just not linked" unless formula.linked_keg.symlink? or formula.keg_only?
-      raise FormulaAlreadyInstalledError, msg
-    end
-
     unless ignore_deps?
       unlinked_deps = formula.recursive_dependencies.map(&:to_formula).select do |dep|
         dep.installed? and not dep.keg_only? and not dep.linked_keg.directory?