webhook: Fix running with no proxies

The fix to the proxy fix did break running with no proxies as ProxyFix doesn't like being passed 0 as the number of proxies.

For this reason the unit tests were also broken. Sigh.

webhook.py

@@ -49,13 +49,14 @@ from flask_dance.consumer import oauth_authorized
 app = Flask(__name__)
 
 proxy_count = int(os.getenv('PROXY_COUNT') or 0)
-# Handle being behind proxies that sets the X-Forwarded-For, -Host and -Proto headers.
-# TODO: Switch to the werkzeug >= 0.15 pattern once it is available in Debian,
-# which currently only ships 0.14
-#  from werkzeug.middleware.proxy_fix import ProxyFix
-#  app.wsgi_app = ProxyFix(app.wsgi_app, x_for=proxy_count, x_host=proxy_count, x_proto=proxy_count)
-from werkzeug.contrib.fixers import ProxyFix
-app.wsgi_app = ProxyFix(app.wsgi_app, num_proxies=proxy_count)
+if proxy_count:
+    # Handle being behind proxies that sets the X-Forwarded-For, -Host and -Proto headers.
+    # TODO: Switch to the werkzeug >= 0.15 pattern once it is available in Debian,
+    # which currently only ships 0.14
+    #  from werkzeug.middleware.proxy_fix import ProxyFix
+    #  app.wsgi_app = ProxyFix(app.wsgi_app, x_for=proxy_count, x_host=proxy_count, x_proto=proxy_count)
+    from werkzeug.contrib.fixers import ProxyFix
+    app.wsgi_app = ProxyFix(app.wsgi_app, num_proxies=proxy_count)
 
 # Queue of Jobs.
 pending = defaultdict(set)