sdk_lib: Encode full sha into version for dev builds in github actions

This gives emerge-gitclone the full sha so that it can fetch by hash from the
remote repository, which lets it succeed for PRs from external contributors.

Signed-off-by: Jeremi Piotrowski <jpiotrowski@microsoft.com>

sdk_lib/sdk_container_common.sh

@@ -55,7 +55,12 @@ function yell() {
 function get_git_version() {
     local tag="$(git tag --points-at HEAD)"
     if [ -z "$tag" ] ; then
-        git describe --tags
+        local abbrev=
+        # emerge-gitclone needs the full SHA for external PRs
+        if [ "${GITHUB_ACTIONS:-}" = "true" ]; then
+            abbrev="--abbrev=40"
+        fi
+        git describe --tags ${abbrev}
     else
         echo "$tag"
     fi