diff -Naur cmake-3.18.2.orig/Modules/FindRuby.cmake cmake-3.18.2/Modules/FindRuby.cmake

--- cmake-3.18.2.orig/Modules/FindRuby.cmake	2020-09-08 13:30:51.129086854 +0000

+++ cmake-3.18.2/Modules/FindRuby.cmake	2020-09-10 07:10:56.679302608 +0000

@@ -300,14 +300,8 @@

   _RUBY_CONFIG_VAR("sitearchdir" Ruby_SITEARCH_DIR)

   _RUBY_CONFIG_VAR("sitelibdir" Ruby_SITELIB_DIR)

-  # vendor_ruby available ?

-  execute_process(COMMAND ${Ruby_EXECUTABLE} -r vendor-specific -e "print 'true'"

-    OUTPUT_VARIABLE Ruby_HAS_VENDOR_RUBY  ERROR_QUIET)

-

-  if(Ruby_HAS_VENDOR_RUBY)

-    _RUBY_CONFIG_VAR("vendorlibdir" Ruby_VENDORLIB_DIR)

-    _RUBY_CONFIG_VAR("vendorarchdir" Ruby_VENDORARCH_DIR)

-  endif()

+  _RUBY_CONFIG_VAR("vendorlibdir" RUBY_VENDORLIB_DIR)

+  _RUBY_CONFIG_VAR("vendorarchdir" RUBY_VENDORARCH_DIR)

   # save the results in the cache so we don't have to run ruby the next time again

   set(Ruby_VERSION_MAJOR    ${Ruby_VERSION_MAJOR}    CACHE PATH "The Ruby major version" FORCE)