class ActiveSupport::BacktraceCleaner

backtrace_cleaner.add_silencer { |line| line =~ /mongrel/ }
# Will reject all lines that include the word "mongrel", like "/gems/mongrel/server.rb" or "/app/my_mongrel_server/rb"

for a given line, it will be excluded from the clean backtrace.
Adds a silencer from the block provided. If the silencer returns +true+

def add_silencer(&block)
  @silencers << block
end