build/bot: configure gpg for non-interactive use

build/bot/ppa-build.sh

@@ -13,7 +13,17 @@ apt-get -yq --no-install-suggests --no-install-recommends install\
 mkdir -p ~/.ssh
 echo '|1|7SiYPr9xl3uctzovOTj4gMwAC1M=|t6ReES75Bo/PxlOPJ6/GsGbTrM0= ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA0aKz5UTUndYgIGG7dQBV+HaeuEZJ2xPHo2DS2iSKvUL4xNMSAY4UguNW+pX56nAQmZKIZZ8MaEvSj6zMEDiq6HFfn5JcTlM80UwlnyKe8B8p7Nk06PPQLrnmQt5fh0HmEcZx+JU9TZsfCHPnX7MNz4ELfZE6cFsclClrKim3BHUIGq//t93DllB+h4O9LHjEUsQ1Sr63irDLSutkLJD6RXchjROXkNirlcNVHH/jwLWR5RcYilNX7S5bIkK8NlWPjsn/8Ua5O7I9/YoE97PpO6i73DTGLh5H9JN/SITwCKBkgSDWUt61uPK3Y11Gty7o2lWsBjhBUm2Y38CBsoGmBw==' >> ~/.ssh/known_hosts
 
-echo "Secret: $PPA_SIGNING_KEY"
+# Configure GPG.
+mkdir -p ~/.gnupg
+
+echo > ~/.gnupg/gpg.conf <<EOF
+use-agent
+pinentry-mode looback
+EOF
+
+echo > ~/.gnupg/gpg-agent.conf <<EOF
+allow-loopback-pinentry
+EOF
 
 # Build the source package and upload.
 go run build/ci.go debsrc -sftp-user geth-ci -signer "Go Ethereum Linux Builder <geth-ci@ethereum.org>"