preserve mk_evar support for type coercions (by Robbert)

2 jobs for !299 with ralf/mk_evar in 5 minutes and 8 seconds (queued for 3 seconds)
latest detached
Status Name Job ID Coverage
  Build
passed build-coq.8.10.2 #135439
fp

00:05:07

passed build-coq.8.13.2-mr #135438
fp

00:04:40