Update urllib3 from 1.21 to 1.21.1 (#2440)

requirements/common.txt

@@ -157,9 +157,9 @@ elasticsearch==5.3.0 --hash=sha256:aea16d6d6ad03a509c9f591eee9ce4ce62918d8ba26bf
 elasticsearch-dsl==5.2.0 --hash=sha256:1a816fed5a0b9cbc862670f3455aa151e75f6042db38a1b008f73cc12173e0d0
 
 # required by elasticsearch
-urllib3==1.21 \
-    --hash=sha256:5589dbd20bae1447a62b55e687e5b5b6024f710ce49b24975b261a3ee4d52276 \
-    --hash=sha256:d0f08f1472754890c8b228106eb831a7a68c93565bd0818936c30bb839913647
+urllib3==1.21.1 \
+    --hash=sha256:8ed6d5c1ff9d6ba84677310060d6a3a78ca3072ce0684cb3c645023009c114b1 \
+    --hash=sha256:b14486978518ca0901a76ba973d7821047409d7f726f22156b24e83fd71382a5
 
 certifi==2017.4.17 \
     --hash=sha256:f4318671072f030a33c7ca6acaef720ddd50ff124d1388e50c1bda4cbd6d7010 \