✅ Simplify pending message for non-CRuby

While it's occassionally nice during debugging to see the entire regexp,
the test name is already part of the pending output.  And some of the
regexps are BIG.

Author: nevans

test/net/imap/test_regexps.rb

@@ -38,7 +38,7 @@ def test_linear_time(data)
     pend "Regexp.linear_time? not implemented by #{RUBY_ENGINE} #{RUBY_ENGINE_VERSION}"
   rescue Test::Unit::AssertionFailedError
     raise if RUBY_ENGINE == "ruby"
-    pend "%p might backtrack in %s %s" % [regexp, RUBY_ENGINE, RUBY_ENGINE_VERSION]
+    pend "might backtrack in %s %s" % [RUBY_ENGINE, RUBY_ENGINE_VERSION]
   end
 
 end