Comment 1 for bug 1552861

Pushed a schema fix to working branch user/jeffdavis/lp1552861-default-match-set-datatype:

http://git.evergreen-ils.org/?p=working/Evergreen.git;a=commitdiff;h=23ad642

I'm not sure how to go about protecting existing values. If they correspond to existing vandelay.match_set.id values, then all is well, but what if they don't? Do we give a warning and wipe invalid values, try to match on vandelay.match_set.name, or...? (As noted above, invalid values already don't work.)