problem in updating CM12 nightly on Moto G XT1033
Here's a stopgap measure to keep your phone updated:

1) Nandroid backup. Necessary

2) Get latest CM12 falcon zip.

3) Copy zip to SD card.

4) Reboot to TWRP.

5) Wipe /cache and /system.

6) Dirty-flash ( common parlance for flashing without wiping userdata) the zip.

7) Cross your fingers and hope it works.

8) If it doesn't, there's your Nandroid backup. Now try a clean flash (in step 5, also wipe /data.

9) It should work (it's like installing a new ROM).

10) The next time onwards, download the OTA zip yourself, compare checksums of the files, copy the OTA zip to your SD card, flash the OTA zip without wiping anything.