either fail or wrong return code when downloading archive

Following to conversion from simpleDownload to downloadWithRetry (see NXBT-1586) in nuxeoServer.sh, the behavior is different and a code 2 is returned when the file already exists. This makes the scripts fail. A workaround is in place for 7.10 and 6.0 with

|| true

at the end of the line.

see nuxeoServer.sh

downloadWithRetry "http://community.nuxeo.com/static/releases/nuxeo-$L_NX_CURR_VR/nuxeo-server-$L_NX_CURR_VR-tomcat.zip" $L_DL_MAX_RETRIES $L_DL_DELAY_RETRY

This should be handled so that it doesn't either stop in debug mode or lose the return code.

A solution may be to initiate a local var with 0 that will hold the return code and use the OR operator instead of true to catch the return code in case of failure.