Revert "tighten up what we can extendfrom"
Revert "tighten up what we can extendfrom"

This reverts commit ff94f01585e40077cbc024ec37b0b7d9ecd842af.

playi/pxt,switch-education/pxt,Microsoft/pxt,switch-education/pxt,switchinnovations/pxt,Microsoft/pxt,switchinnovations/pxt,playi/pxt,playi/pxt,playi/pxt,switch-education/pxt,Microsoft/pxt,switchinnovations/pxt,Microsoft/pxt,switch-education/pxt,Microsoft/pxt,switch-education/pxt,switchinnovations/pxt