For whatever reason (may be a bug in the DM, or in the seralizer, or in selser), whitespace preservation didn't work in this edit https://en.wikipedia.org/w/index.php?title=International_Air_Transport_Association_airport_code&diff=530666305&oldid=526301045 . The whitespace changes didn't show in the initial diff I was asked to verify, only in the final change.
Version: unspecified
Severity: normal
Confirm not happening in live - but /does/ happen with heads of VisualEditor and Parsoid (and MediaWiki) in testing. As Roan says, doesn't appear in diff, does appear in the final change.
It looks like this is happening because getDomFromData() somehow messes up the whitespace information. Then when getDomFromData() runs a second time (because you go back, change things, then diff again, or if you save after diffing), it sees inconsistent whitespace information and refuses to serialize it.
Related URL: https://gerrit.wikimedia.org/r/59570 (Gerrit Change Ic4c93510518163894201a693ab50331413715967)
(In reply to comment #3)
Related URL: https://gerrit.wikimedia.org/r/59570 (Gerrit Change
Ic4c93510518163894201a693ab50331413715967)
This commit fixes the bug. CC Gabriel and Subbu because they'd probably like to test it.