exe/benchmark-driver in benchmark_driver-0.15.3 vs exe/benchmark-driver in benchmark_driver-0.15.4

@@ -45,10 +45,10 @@
     end
     o.on('--rbenv VERSIONS', String, 'Ruby executables in rbenv (x.x.x arg1;y.y.y arg2;...)') do |r|
       r.split(';').each do |version|
         executables << BenchmarkDriver::Rbenv.parse_spec(version)
       end
-    end if system("which rbenv > #{File::NULL}")
+    end if system("which rbenv > #{File::NULL} 2>&1")
     o.on('--ridkuse VERSIONS', String, 'Ruby executables in ridk use (x.x.x arg1;y.y.y arg2;...) for RubyInstaller2 on Windows') do |r|
       r.split(';').each do |version|
         executables << BenchmarkDriver::RidkUse.parse_spec(version)
       end
     end if system("ridk version > #{File::NULL} 2>&1")