Enable pipefail, nounset; Simplify some checks

scripts/backup.sh

@@ -1,6 +1,8 @@
 #!/bin/sh
 
-set -e
+set -o errexit
+set -o nounset
+set -o pipefail
 
 REPOSITORY=https://github.com/descartes-underwriting/devops-technical-test-data.git
 BRANCH=main
@@ -116,9 +118,7 @@ do
         fi
 
         # Retrieve file state (Added, Modified, Deleted)
-        # Using basic regex as we want to avoid checking '()' or other complex regex patterns.
-        # This is suboptimal and error prone. But it passes the full backup :-)
-        STATE=$(${GIT} ${GIT_OPTS[@]} show --name-status --pretty= ${COMMIT_SHA} | grep -G "^..${FILE}\$" | cut -f1)
+        STATE=$(${GIT} ${GIT_OPTS[@]} show --name-status --pretty= ${COMMIT_SHA} -- "${FILE}" | cut -f1)
 
         if test "${STATE}" != "D"
         then