unable to unlock screen because keyboard grabbed by gcr-prompter (gpg password prompt)

[Jamie Strandboge]

On Trusty, last night I left my computer with thunderbird running and the screen locked (good). I configure gpg to only cache my passphrase for a few minutes instead of remembering it for the whole session. When I came back to unlock the screen, the password dialog would not accept keyboard input until I pressed 'Enter', and then I could type in my password to unlock the screen. When I then unlocked the screen, I noticed that thunderbird was prompting for me to enter my gpg passphrase. What appeared to happen was the screen locked and then sometime later thunderbird received an encrypted email and prompted me for my gpg passphrase. I would expect for the screenlock to always accept my keyboard input and only after would the gpg passphrase dialog accept input.

Here are the related processes that are running when I am being prompted:
jamie 5544 0.0 0.0 23296 1656 ? SL 08:04 0:00 /usr/bin/gpg --charset utf-8 --display-charset utf-8 --batch --no-tty --status-fd 2 --decrypt --use-agent
jamie 5552 0.0 0.2 710844 18960 ? SLl 08:04 0:00 /usr/lib/gcr/gcr-prompter
jamie 21612 0.0 0.0 16376 216 ? Ss Jun19 0:01 gpg-agent --daemon --sh

(gcr-prompter is from the 'gcr' package whose description says 'GNOME crypto services (daemon and tools)'. I'm not sure if this is a duplicate of another bug but I filed this one to be sure.