Remove histogram from PTable and some minor fixes

4 jobs for master in 4 minutes and 57 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Build
passed build #1200
grouprunner

00:02:47

failed coverage #1203
grouprunner

00:02:09

failed coverage #1201
grouprunner

00:02:14

 
  Test
skipped test #1202
grouprunner
 
Name Stage Failure
failed
coverage Build
	 19 - tree_split (Failed)
20 - tree_erase (Failed)
21 - tree_balance (Failed)
22 - tree_merge (Failed)
23 - scan (Failed)
24 - point (Failed)
Errors while running CTest
Authenticating with credentials from /root/.docker/config.json
ERROR: Job failed: exit code 1