fixup! Revert predicate_functions changes

Author: pirj

script/predicate_functions.sh

@@ -2,15 +2,19 @@
 # DO NOT modify it by hand as your changes will get lost the next time it is generated.
 
 function is_mri {
-  if ruby -e "exit(RUBY_ENGINE == 'ruby')"; then
+  if ruby -e "exit(!defined?(RUBY_ENGINE) || RUBY_ENGINE == 'ruby')"; then
+    # RUBY_ENGINE only returns 'ruby' on MRI.
+    # MRI 1.8.7 lacks the constant but all other rubies have it (including JRuby in 1.8 mode)
     return 0
   else
     return 1
   fi;
 }
 
 function is_jruby {
-  if ruby -e "exit(RUBY_PLATFORM == 'java')"; then
+  if ruby -e "exit(defined?(RUBY_PLATFORM) && RUBY_PLATFORM == 'java')"; then
+    # RUBY_ENGINE only returns 'ruby' on MRI.
+    # MRI 1.8.7 lacks the constant but all other rubies have it (including JRuby in 1.8 mode)
     return 0
   else
     return 1
@@ -69,14 +73,22 @@ function rspec_rails_compatible {
   fi
 }
 
+function rspec_support_compatible {
+  if [ "$MAINTENANCE_BRANCH" != "2-99-maintenance" ] && [ "$MAINTENANCE_BRANCH" != "2-14-maintenance" ]; then
+    return 0
+  else
+    return 1
+  fi
+}
+
 function additional_specs_available {
   type run_additional_specs > /dev/null 2>&1
   return $?
 }
 
 function documentation_enforced {
   if [ -x ./bin/yard ]; then
-    if is_mri; then
+    if is_mri_2plus; then
       return 0
     else
       return 1