merge revision(s) 53943: [Backport #11969]
* lib/irb.rb: avoid to needless truncation when using back_trace_limit option. [fix GH-1205][ruby-core:72773][Bug #11969]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@54322 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 53943: [Backport #11969]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@54322 b2dd03c8-39d4-4d8f-98ff-823fe69b080e