Updated diff-sha.sh

Author: jackton1

diff-sha.sh

@@ -74,7 +74,7 @@ else
     if [[ "$INPUT_USE_FORK_POINT" == "true" ]]; then
       echo "Getting fork point..."
       git fetch --no-tags -u --progress temp_changed_files "${TARGET_BRANCH}":"${TARGET_BRANCH}" && exit_status=$? || exit_status=$?
-      PREVIOUS_SHA=$(git merge-base --fork-point "${TARGET_BRANCH}") && exit_status=$? || exit_status=$?
+      PREVIOUS_SHA=$(git merge-base --fork-point "temp_changed_files/${TARGET_BRANCH}") && exit_status=$? || exit_status=$?
     else
       git fetch --no-tags -u --progress --depth=1 temp_changed_files "${TARGET_BRANCH}":"${TARGET_BRANCH}" && exit_status=$? || exit_status=$?
       PREVIOUS_SHA=$(git rev-list --no-merges -n 1 "${TARGET_BRANCH}" 2>&1) && exit_status=$? || exit_status=$?