Updating get_compute_library.sh to handle ACL release branches.

* CLFRAMEWORKREVISION in this script can be a SHA or a branch
  specifier. If it is a branch we need to pull.

Signed-off-by: Colm Donelan <Colm.Donelan@arm.com>
Change-Id: Ibc46f803817b2c8983ebb9720417a1bd90679f9e
diff --git a/scripts/get_compute_library.sh b/scripts/get_compute_library.sh
index a6f114f..ea67d7e 100755
--- a/scripts/get_compute_library.sh
+++ b/scripts/get_compute_library.sh
@@ -75,6 +75,12 @@
 
 git fetch && git fetch https://review.mlplatform.org/ml/ComputeLibrary && git checkout ${CLFRAMEWORKREVISION}
 AssertZeroExitCode "Fetching and checking out ${CLFRAMEWORKREVISION} failed"
+# If the target ACL revision includes a branch we also need to do a pull.
+# This generally occurs with a release branch.
+if [[ "${CLFRAMEWORKREVISION}" == *"branches"* ]]; then
+    git pull
+    AssertZeroExitCode "ACL reference includes a branch but git pull failed."
+fi
 
 # Set commit hook so we can submit reviews to gerrit
 (curl -Lo `git rev-parse --git-dir`/hooks/commit-msg https://review.mlplatform.org/tools/hooks/commit-msg; chmod +x `git rev-parse --git-dir`/hooks/commit-msg)