ci: fix static checks merge base resolution

This change fetches the full history of the base branch and the change
under test, to avoid problems with unreachable commits.

Signed-off-by: Chris Kay <chris.kay@arm.com>
Change-Id: I7ed38a65678552fff5b0f5efabf6bafc06ea86ee
Signed-off-by: Tomás González <tomasagustin.gonzalezorlando@arm.com>
diff --git a/script/next-checks/next-checks-generic-tests.sh b/script/next-checks/next-checks-generic-tests.sh
index faf5802..599ff29 100755
--- a/script/next-checks/next-checks-generic-tests.sh
+++ b/script/next-checks/next-checks-generic-tests.sh
@@ -21,8 +21,7 @@
 # next tests, usually this will be tfa-next
 export GERRIT_BRANCH=${GERRIT_BRANCH:="tfa-next"}
 
-# git operations e.g. ${get_merge_base} rely on access to tfa-next branch,
-# we need to access via SSH for that to work currently
+# git operations rely on access to tfa-next branch, we need to access via SSH for that to work currently
 SSH_PARAMS="-o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o PubkeyAcceptedKeyTypes=+ssh-rsa -p 29418 -i ${CI_BOT_KEY}"
 REPO_SSH_URL="ssh://${CI_BOT_USERNAME}@review.trustedfirmware.org:29418/${REPO_SPACE}/${REPO_NAME}"
 export GIT_SSH_COMMAND="ssh ${SSH_PARAMS}"