Standalone mode disables multiple jobs on compiling directory

It seems since the release of version 3 compiling an entire directory with --standalone --jobs <some_number_or_"sys"> always results in a single compiler process, building each file in the directory one after another.
(Standalone mode is necessary due to #720)

Error given is CoconutWarning: got --jobs <some_number_or_"sys"> but only compiling one file; disabling --jobs