Try using executemany().  Refs #11287, 9648.
Try using executemany().  Refs #11287, 9648.

This is only one place that needs it but I'd like to see if this fixes
falkb's problem.  Or at least let's him get further along.

git-svn-id: 2159781fc7c14c6bdd1f7e265daf7a25099c31e7@13369 7322e99d-02ea-0310-aa39-e9a107903beb

trac-hacks/trac-jsGantt,trac-hacks/trac-jsGantt,trac-hacks/trac-jsGantt