Ensure ENV is pristine for each installation

Because we modified the ENV global each install this propagated to consecutive
formulae. So exec a new brew process each install. This is the safest way
although Ruby exceptions don't propagate to the parent process so I worry
about it somewhat.

Library/Homebrew/brew.h.rb

@@ -179,7 +179,7 @@ def prune
   else
     # always showing symlinks text is deliberate
     print "Pruned #{$n} symbolic links "
-    print "and #{$n} directories " if $d > 0
+    print "and #{$d} directories " if $d > 0
     puts  "from #{HOMEBREW_PREFIX}"
   end
 end

Library/Homebrew/keg.rb

@@ -38,7 +38,7 @@ class Keg <Pathname
     # these dirs REMEMBER that *NOT* everything needs to be in the main tree
     link_dir('etc') {:mkpath}
     link_dir('bin') {:link}
-    link_dir('lib') {|path| :mkpath if %w[pkgconfig php].include? path.to_s}
+    link_dir('lib') {|path| :mkpath if %w[pkgconfig php perl5].include? path.to_s}
     link_dir('include') {:link}
     link_dir('share') {|path| :mkpath if mkpaths.include? path.to_s}
 

bin/brew

@@ -52,10 +52,24 @@ begin
       end
 
     when 'install'
-      require 'keg'
+      # we need to ensure a pristine ENV for each process or the formula
+      # will start with the ENV from the previous build
       ARGV.formulae.each do |f|
+        pid=fork
+        if pid.nil?
+          exec "brew", "install-just-one", f.name, *ARGV.options
+        else
+          Process.wait pid
+        end
+        exit! 1 if $? != 0 # exception in other brew will be visible on screen
+      end
+
+    # this is an internal option, don't expose it to the user
+    when 'install-just-one'
+      require 'keg'
+      f=ARGV.formulae.shift
       raise "#{f.name} is already installed" if f.installed? unless ARGV.force?
-        start_time=Time.now
+      BEGINNING=Time.now
       begin
         install f
         ohai "Caveats", f.caveats, ''
@@ -63,12 +77,11 @@ begin
         clean f
         raise "Nothing was installed to #{f.prefix}" unless f.installed?
         Keg.new(f.prefix).link
-        rescue
+      rescue Exception
         f.prefix.rmtree if f.prefix.directory?
         raise
       end
-        puts "#{f.prefix}: "+f.prefix.abv+", built in #{pretty_duration Time.now-start_time}"
-      end
+      puts "#{f.prefix}: #{f.prefix.abv}, built in #{pretty_duration Time.now-BEGINNING}"
 
     when 'ln', 'link'
       ARGV.kegs.each {|keg| puts "#{keg.link} links created for #{keg}"}