Set VERBOSE and HOMEBREW_LOG in `brew sh`

Library/Homebrew/cmd/sh.rb

@@ -9,13 +9,16 @@ module Homebrew extend self
     end
     ENV.setup_build_environment
     ENV['PS1'] = 'brew \[\033[1;32m\]\w\[\033[0m\]$ '
+    ENV['VERBOSE'] = '1'
+    ENV['HOMEBREW_LOG'] = '1'
     puts <<-EOS.undent_________________________________________________________72
-         Your shell has been configured to use Homebrew's build environment: this
-         should help you build stuff. Notably though, the system versions of gem
-         and pip will ignore our configuration and insist on using the
+           Your shell has been configured to use Homebrew's build environment:
+         this should help you build stuff. Notably though, the system versions of
+         gem and pip will ignore our configuration and insist on using the
          environment they were built under (mostly). Sadly, scons will also
          ignore our configuration.
-         When done, type `exit'.
+           All toolchain use will be logged to: ~/Library/Homebrew/Logs/cc.log
+           When done, type `exit'.
          EOS
     exec ENV['SHELL']
   end