union plan node memory leak
Re-apply ENG-4008 changeset.
Fix the sqlcoverage merge issue between the union and numeric functions changesets.
bug fixes
Made union executors stateless - no need for reset
Merge branch 'master' into ENG-4008-retry
ENG-4155: Perhaps address pmartel feedback.
Merge remote-tracking branch 'alexeev/eng_3217' into ENG-3217
sqlcoverage re-enable parenthesized union tests and fix some "suddenly?" non-deterministic cases
Merge branch 'master' into ENG-3217
Add checks to make sure that messages aren't delivered from failed hosts
Merge remote-tracking branch 'origin/master' into ENG-3217
For ENG-4135, fix bugs in ExportManager surround turning export on/off at runtime.
ENG-4178: Fix the schema to allow 0 or 1 snapshot elements within
partition-detection element.  Fix CatalogUtil to provide appropriate
default when not specified.  Add parsing and catalog content test
cases.
ENG-4122: Detect the case of a node attempting to rejoin to itself
earlier and print a sane error message.
Merge branch 'master' into ENG-4135
Make field private based on code review
ENG-4158, ENG-4164, ENG-4172: Just avoid doing any snapshot work
at all on a node which has any rejoining sites.  All snapshot fragments
get returned the rejoining status, and no site on a rejoining node ever
touches any of the snapshot machinery until all sites are fully
rejoined.
Add more machinery to dump the state of the system when the MPI
deadlocks.
Fixes for status dump based on code review.