Replace on host rather than socket, feedback:

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10156#note_26812377

scripts/prepare_build.sh

@@ -14,7 +14,7 @@ if [ -f /.dockerenv ] || [ -f ./dockerinit ]; then
     else # Assume it's mysql
         sed -i 's/username:.*/username: root/g' config/database.yml
         sed -i 's/password:.*/password:/g' config/database.yml
-        sed -i 's/# socket:.*/host: mysql/g' config/database.yml
+        sed -i 's/# host:.*/host: mysql/g' config/database.yml
     fi
 
     cp config/resque.yml.example config/resque.yml