Tests: Improve FindRuby test robustness

Tests/FindRuby/CMakeLists.txt

@@ -24,7 +24,7 @@ if(CMake_TEST_FindRuby)
     --test-command ${CMAKE_CTEST_COMMAND} -V -C $<CONFIGURATION>
     )
   set_tests_properties(FindRuby.Fail PROPERTIES
-    PASS_REGULAR_EXPRESSION "Could NOT find Ruby.*(Required is at least version \"[0-9]+\\.[0-9]+\\.[0-9]+\")")
+    PASS_REGULAR_EXPRESSION "Could NOT find Ruby.*(Required[ \n]+is[ \n]+at[ \n]+least[ \n]+version[ \n]*\"[0-9]+\\.[0-9]+\\.[0-9]+\")")
 
   # Looks for 1.9.9 EXACTLY, which unlike the "FindRuby" test above will fail on every machine
   # since this version doesn't exist (ruby goes from 1.9.3 to 2.0.0)

Tests/FindRuby/Rvm/CMakeLists.txt

@@ -23,7 +23,7 @@ if (result)
   message (FATAL_ERROR "Unable to detect RVM ruby version from `${MY_RUBY_HOME}/bin/ruby`: ${RVM_RUBY_VERSION}")
 endif()
 
-execute_process(COMMAND "${CMAKE_COMMAND}" -E env --unset=MY_RUBY_HOME --unset=PATH
+execute_process(COMMAND "${CMAKE_COMMAND}" -E env --unset=MY_RUBY_HOME PATH=/usr/bin:/bin
                         "which" "ruby"
                  RESULT_VARIABLE result
                  OUTPUT_VARIABLE SYSTEM_RUBY