Make the script for getting the compute library more robust

 * Added an extra git fetch without specifying the remote to
   allow fetching from wathever remote one is using
 * Fixes a failure in our setup agents jobs

Change-Id: I64b034eec5fba5c8b113e89b5bb5724fb978e511
Signed-off-by: Matteo Martincigh <matteo.martincigh@arm.com>
diff --git a/scripts/get_compute_library.sh b/scripts/get_compute_library.sh
index 9312504..39de20c 100755
--- a/scripts/get_compute_library.sh
+++ b/scripts/get_compute_library.sh
@@ -73,7 +73,7 @@
     CLFRAMEWORKREVISION=$CLFRAMEWORK_SHA
 fi
 
-git fetch https://review.mlplatform.org/ml/ComputeLibrary && git checkout ${CLFRAMEWORKREVISION}
+git fetch && git fetch https://review.mlplatform.org/ml/ComputeLibrary && git checkout ${CLFRAMEWORKREVISION}
 AssertZeroExitCode "Fetching and checking out ${CLFRAMEWORKREVISION} failed"
 
 # Set commit hook so we can submit reviews to gerrit