Default script to not generate prototypes in #19

The intent is to set the remote and branch prefix filter to empty as a
default to current behavior locally. In the Makefile, it will default to
the correct remote and empty branch to skip. The GHA workflow argument
should override and run that.

support/list_revisions.sh

@@ -17,12 +17,18 @@ TAGGED_REVISIONS=$(echo "${TAGGED_REVISIONS}" | sort -t "." -k1,1n -k2,2n -k3,3n
 
 # retrieve prefix for branches of prototypes to be listed and published and if
 # it is empty, it can be ignored.
-PROTOTYPE_BRANCHES_REMOTE=${PROTOTYPE_BRANCHES_REMOTE:-"origin"}
-PROTOTYPE_BRANCHES_PREFIX=${PROTOTYPE_BRANCHES_PREFIX:-"prototype"}
-# the output of ls-remote is the best for this but doesn't have ready-made
-# format or pretty-print options. We need to use sed to filter the output
-# output is the following format:
-# sha1-hash        refs/heads/branch-name
-# 012345abcd012345abcd012345abcd012345abcd        refs/heads/branch-name
-PROTOTYPE_BRANCHES=$(cd "${OSCAL_DIR}"; git ls-remote "${PROTOTYPE_BRANCHES_REMOTE}" "${PROTOTYPE_BRANCHES_PREFIX}*" | sed -n -e "s|^.*\(refs/heads/\)\(${PROTOTYPE_BRANCHES_PREFIX}\)|\2|p")
-echo "${TAGGED_REVISIONS}" "${PROTOTYPE_BRANCHES}"
+PROTOTYPE_BRANCHES_REMOTE=${PROTOTYPE_BRANCHES_REMOTE:-""}
+PROTOTYPE_BRANCHES_PREFIX=${PROTOTYPE_BRANCHES_PREFIX:-""}
+
+if [[ -z "${PROTOTYPE_BRANCHES_PREFIX}" || -z "${PROTOTYPE_BRANCHES_REMOTE}" ]]; then
+    # the default values are empty, do nothing
+    echo "${TAGGED_REVISIONS}"
+else
+    # the output of ls-remote is the best for this but doesn't have ready-made
+    # format or pretty-print options. We need to use sed to filter the output
+    # output is the following format:
+    # sha1-hash        refs/heads/branch-name
+    # 012345abcd012345abcd012345abcd012345abcd        refs/heads/branch-name
+    PROTOTYPE_BRANCHES=$(cd "${OSCAL_DIR}"; git ls-remote "${PROTOTYPE_BRANCHES_REMOTE}" "${PROTOTYPE_BRANCHES_PREFIX}*" | sed -n -e "s|^.*\(refs/heads/\)\(${PROTOTYPE_BRANCHES_PREFIX}\)|\2|p")
+    echo "${TAGGED_REVISIONS}" "${PROTOTYPE_BRANCHES}"
+fi