Wait for pidfile to exist when starting with Redhat init script

Fixes #5359

Docker-DCO-1.1-Signed-off-by: Chris St. Pierre <chris.a.st.pierre@gmail.com> (github: stpierre)
Upstream-commit: a598dba1346c9f2e878e8250a9d641a2206cb4e5
Component: engine

components/engine/contrib/init/sysvinit-redhat/docker

@@ -49,6 +49,11 @@ start() {
         $exec -d $other_args &>> $logfile &
         pid=$!
         touch $lockfile
+        # wait for the pidfile to exist.  see
+        # https://github.com/dotcloud/docker/issues/5359
+        while [ ! -f $pidfile ]; do
+            sleep 1
+        done
         success
         echo
     else