Extract installer setup to prelude method

Library/Homebrew/cmd/install.rb

@@ -104,6 +104,7 @@ module Homebrew extend self
 
   def install_formula f
     fi = FormulaInstaller.new(f)
+    fi.prelude
     fi.install
     fi.caveats
     fi.finish

Library/Homebrew/cmd/upgrade.rb

@@ -59,6 +59,7 @@ module Homebrew extend self
     installer = FormulaInstaller.new(f)
     installer.options |= Tab.for_formula(f).used_options
     installer.show_header = false
+    installer.prelude
 
     oh1 "Upgrading #{f.name}"
 

Library/Homebrew/formula_installer.rb

@@ -30,10 +30,6 @@ class FormulaInstaller
 
     @poured_bottle = false
     @pour_failed   = false
-
-    verify_deps_exist unless ignore_deps
-    lock
-    check_install_sanity
   end
 
   def pour_bottle? install_bottle_options={:warn=>false}
@@ -41,6 +37,12 @@ class FormulaInstaller
     options.empty? && install_bottle?(f, install_bottle_options)
   end
 
+  def prelude
+    verify_deps_exist unless ignore_deps
+    lock
+    check_install_sanity
+  end
+
   def verify_deps_exist
     f.recursive_dependencies.map(&:to_formula)
   rescue TapFormulaUnavailableError => e
@@ -311,6 +313,7 @@ class FormulaInstaller
     fi.ignore_deps = true
     fi.only_deps = false
     fi.show_header = false
+    fi.prelude
     oh1 "Installing #{f} dependency: #{Tty.green}#{dep.name}#{Tty.reset}"
     outdated_keg.unlink if outdated_keg
     fi.install