Fix common systemd pitfalls die msg

That change introduces correct way of generating msg
for die in common systemd pitfalls.

Co-Authored-By: Szymon Datko <szymon.datko@corp.ovh.com>
Co-Authored-By: Piotr Bielak <piotr.bielak@corp.ovh.com>
Change-Id: I28aebffce6c5561360a9e44c1abc44b709054c30

Author: 3 people

functions-common

@@ -1439,7 +1439,7 @@ function _common_systemd_pitfalls {
     # do some sanity checks on $cmd to see things we don't expect to work
 
     if [[ "$cmd" =~ "sudo" ]]; then
-        local msg=<<EOF
+        read -r -d '' msg << EOF || true  # read returns 1 for EOF, but it is ok here
 You are trying to use run_process with sudo, this is not going to work under systemd.
 
 If you need to run a service as a user other than $STACK_USER call it with:
@@ -1450,7 +1450,7 @@ EOF
     fi
 
     if [[ ! "$cmd" =~ ^/ ]]; then
-        local msg=<<EOF
+        read -r -d '' msg << EOF || true  # read returns 1 for EOF, but it is ok here
 The cmd="$cmd" does not start with an absolute path. It will fail to
 start under systemd.