This explains that if you change your torrc to do more, you might
need to change tor.service.in to allow it. See #15195.
+# tor.service -- this systemd configuration file for Tor sets up a
+# relatively conservative, hardened Tor service. You may need to
+# edit it if you are making changes to your Tor configuration that it
+# does not allow. Package maintainers: this should be a starting point
+# for your tor.service; it is not the last point.
+
[Unit]
Description = Anonymizing overlay network for TCP
After = syslog.target network.target nss-lookup.target