MapServer crashes on simple WCS requests.
Valgrind dump attanched here : https://gist.github.com/gsueur/6069674
fix crashes on error'd WCS getcoverage requests (#4714)
initialise msWCSGetCoverageMetadata20 to NULL to avoid memory failures
ping @Schpidi . @gsueur please test the current fix. You're going to be running into other (hopefully user) issues as this was failing on an error condition.