Fix GIT_REV on dokku

bin/pre-deploy

@@ -7,7 +7,7 @@ db: relay.jsonld
 
 # Listener
 listen: 0.0.0.0
-port: ${PORT:-8080}
+port: ${PORT:-5000}
 
 # Note
 note: "Make a note about your instance here."

relay/nodeinfo.py

@@ -1,3 +1,4 @@
+import os
 import subprocess
 import urllib.parse
 
@@ -10,7 +11,7 @@ from .database import DATABASE
 try:
     commit_label = subprocess.check_output(["git", "rev-parse", "HEAD"]).strip().decode('ascii')
 except:
-    commit_label = '???'
+    commit_label = os.environ.get('GIT_REV')
 
 
 nodeinfo_template = {