Merge branch '96-balanced-set' into 'master'

Fix tests for Data.Set; use balanced invariant instead of log_size (which was always True)

Closes #96

See merge request !340
1 job for master in 2 minutes and 16 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #102549
test-nightly

00:02:16