bootstraptest/runner.rb: first line in the source

* bootstraptest/runner.rb (pretty): remove empty line at the
  beginning only.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56394 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

bootstraptest/runner.rb

@@ -405,7 +405,7 @@ def flunk(message = '')
 end
 
 def pretty(src, desc, result)
-  src = src.sub(/\A.*\n/, '')
+  src = src.sub(/\A[\s\t]*\n/, '')
   (/\n/ =~ src ? "\n#{adjust_indent(src)}" : src) + "  #=> #{desc}"
 end