Description of problem:
"rpm --resign" interoperates badly with gpg2 when the key is encrypted

Version-Release number of selected component (if applicable):
gnupg2-2.1.4-1.fc22.x86_64
rpm-sign-4.12.0.1-9.fc22.x86_64


How reproducible:
Always


Steps to Reproduce:
1. Set up a minimal Fedora 22 system
2. dnf install rpm-sign
3. gpg2 --gen-key
4. create a key for user 'test test', a loop that repeatedly issues "find / -type f -print" will help you with entropy creation, otherwise takes a really long time.
5. choose a password. I picked 'a'.
6. echo "%_gpg_name test" > .rpmmacros
7. dnf download rpm
8. rpm --resign rpm*rpm
9. enter your simple password, 'a' when prompted

Actual results:
[noa@localhost ~]$ rpm --resign rpm-4.12.0.1-9.fc22.x86_64.rpm 
Enter pass phrase: 
gpg: signing failed: Inappropriate ioctl for device
gpg: signing failed: Inappropriate ioctl for device
Pass phrase check failed or gpg key expired


Expected results:
the package res-signed with my newly created key

Additional info:
I guess this default behaviour will encourage people to use passwordless keys, which seems like a really bad side effect of the change that gpg2 really tries to get people to provide passwords interactively.

I'm assuming the fix is to provide gpg-agent with access to the tty to create a proper password prompt.