Fingerprint reader login and aborting credentials verification phase

[m4l352k4]

I've had troubles to find correct PAM config for fingerprint reader login. The best results I've got are with this simple config:

auth        sufficient pam_fprintd.so
...

You have to first type anything in the password box (or leave it blank) and press Enter, and then during the "Verifying credentials" phase you scan your fingerprint with the sensor. The problem is that sometimes fingers are wet and you'd prefer to relogin with the password but lemurs seem to endlessly wait until fingerprint sensor succeeds.

For most apps, pressing <c-c> works and makes the app fallback to the password input. Is there some similar shortcut in lemurs to abort "Verifying credentials" or is there some better pam config for password backup?