irb: improve pry config

The idea here is that the pry session history
should be separate for homebrew than the global
pry history.

We also ignore any .pryrc files so that they
don't interfere with this config.

Library/Homebrew/dev-cmd/irb.rb

@@ -54,7 +54,6 @@ def irb
     if args.pry?
       Homebrew.install_gem_setup_path! "pry"
       require "pry"
-      Pry.config.prompt_name = "brew"
     else
       require "irb"
     end
@@ -65,6 +64,11 @@ def irb
 
     ohai "Interactive Homebrew Shell", "Example commands available with: `brew irb --examples`"
     if args.pry?
+      Pry.config.should_load_rc = false # skip loading .pryrc
+      Pry.config.history_file = (HOMEBREW_REPOSITORY/".pry_history").to_s
+      Pry.config.memory_size = 100 # max lines to save to history file
+      Pry.config.prompt_name = "brew"
+
       Pry.start
     else
       ENV["IRBRC"] = (HOMEBREW_REPOSITORY/".irb_config").to_s