delete from :number until the end

railties/lib/rails/engine.rb

@@ -335,7 +335,7 @@ def inherited(base)
         unless base.abstract_railtie?
           base.called_from = begin
             # Remove the line number from backtraces making sure we don't leave anything behind
-            call_stack = caller.map { |p| p.split(':')[0..-2].join(':') }
+            call_stack = caller.map { |p| p.sub(/:\d+.*/, '') }
             File.dirname(call_stack.detect { |p| p !~ %r[railties[\w.-]*/lib/rails|rack[\w.-]*/lib/rack] })
           end
         end