Comment 8 for bug 2056080

Yes, unfortunately there is no easy way to upgrade between update1 & the fix. One has to purge the buggy package first :/

That's why the sooner this is uploaded the better, in the hope that as few people as possible have them installed.

You can also have a look at the conversation in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1065668 which mentions the same problem & how to proceed (ie purge the old packages).