Fix issue that prevented freight-cache from working with GnuPG 2.x

URL: #72
Signed-off-by: Samuli Seppänen <samuli@openvpn.net>

Author: mattock

README.md

@@ -27,6 +27,10 @@ Build the cache of all the files needed to be accepted as a Debian archive:
 
 	freight cache
 
+If your system has GnuPG 2.x make sure that a gpg-agent is running or the above
+command will fail. Also make sure you have installed a pinentry package (e.g.
+pinentry-curses) that suits your needs.
+
 Serve `/var/cache/freight` via your favorite web server and install it as an APT source:
 
 	echo "deb http://example.com $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/example.list

lib/freight/apt.sh

@@ -207,6 +207,12 @@ EOF
 
     } >"$DISTCACHE/Release"
 
+    # Pinentry may fail on GnuPG 2.x without GPG_TTY
+    #
+    # https://github.com/freight-team/freight/issues/72
+    #
+    export GPG_TTY=$(tty)
+
     # Sign the top-level `Release` file with `gpg`, for each key and
     # concatenate signatures.
     for GPGKEY in $GPG; do