.exports: Add GPG_TTY

Author: mathiasbynens

.exports

@@ -28,3 +28,7 @@ export LESS_TERMCAP_md="${yellow}";
 
 # Don’t clear the screen after quitting a manual page.
 export MANPAGER='less -X';
+
+# Avoid issues with `gpg` as installed via Homebrew.
+# https://stackoverflow.com/a/42265848/96656
+export GPG_TTY=$(tty);