Wikimedia Bugzilla is closed!

Currently, it's possible to put this into wikiversions.dat:
enwiki php-1.onemillonandsomething

...even though this file:
/usr/local/apache/common-local/php-1.onemillonandsomething/index.php

...doesn't exist and hopefully never will.  That means running refreshWikiversionsCDB will cause a fatal on the enwiki homepage.

Solution: do a sanity check prior to building the cdb file, and make sure that for each specified version "foo", that this file exists:

/usr/local/apache/common-local/foo/index.php

...and exit with a fatal error if it doesn't, leaving the cdb file unscathed.