[COMMON] Fix condition equality bashisms

pointed out by checkbashisms.

$ mycmd=$(tox -e checkbashisms | grep "(should be 'b = a')" | sed -e
  "s@^[^.]*\(.[^ ]*\) line \([0-9]*\) .*@sed -i -e '\2s/==/=/g' \1;@")

$ eval $mycmd

Issue-ID: OOM-2643
Signed-off-by: Guillaume Lambert <guillaume.lambert@orange.com>
Change-Id: I9032130bc4717e111de11a73187c2f1052376e45
diff --git a/kubernetes/common/music/resources/config/startup.sh b/kubernetes/common/music/resources/config/startup.sh
index 37bb84d..e3cee36 100755
--- a/kubernetes/common/music/resources/config/startup.sh
+++ b/kubernetes/common/music/resources/config/startup.sh
@@ -32,8 +32,8 @@
 # Debug Setup. Uses env variables
 # DEBUG and DEBUG_PORT
 # DEBUG=true/false | DEBUG_PORT=<Port valie must be integer>
-if [ "${DEBUG}" == "true" ]; then
-  if [ "${DEBUG_PORT}" == "" ]; then
+if [ "${DEBUG}" = "true" ]; then
+  if [ "${DEBUG_PORT}" = "" ]; then
     DEBUG_PORT=8000
   fi
   echo "Debug mode on"