Use patched supervisor-stdout module

It includes following fixes:

- coderanger/supervisor-stdout#12
- coderanger/supervisor-stdout#18
- coderanger/supervisor-stdout#20

Fixes #736

Author: nijel

requirements.txt

@@ -20,7 +20,11 @@ git-review==1.28.0
 google-cloud-translate==2.0.1
 hiredis==1.1.0
 httpretty==1.0.2
-https://github.com/coderanger/supervisor-stdout/archive/87d672c72664f89250f08693505e02d0905926a1.zip
+# Patched supervisor-stdout with following fixes:
+# - https://github.com/coderanger/supervisor-stdout/pull/12
+# - https://github.com/coderanger/supervisor-stdout/pull/18
+# - https://github.com/coderanger/supervisor-stdout/pull/20
+https://github.com/nijel/supervisor-stdout/archive/c909c1a1ddabaf679dc2eaecb3b8f5ad6bef467a.zip
 iniparse==0.5
 jellyfish==0.8.2
 kombu==4.6.11