Handle 'git checkout' error gracefully

Previous commit was focused on portzap-pull.
This one covers portzap-clone.

libexec/portzap/portzap-clone

@@ -8,6 +8,7 @@ git="${localbase}"/bin/git
 giturl=$1
 gitdir=$2
 branch=$3
+mode="u=rwX,g=rwX,o="
 
 ##
 # main
@@ -23,11 +24,17 @@ if [ -e "${gitdir}/.git" ]; then
 fi
 
 set -x
-umask u=rwX,g=rwX,o=
+umask "${mode}"
 doas -u _portzap "${git}" clone "${giturl}" "${gitdir}"
 cd "${gitdir}"
 doas -u _portzap "${git}" config core.filemode off
-set +x +e
-echo "[-] Checkout ${branch}"
-doas -u _portzap "${git}" checkout -t origin/"${branch}" > /dev/null 2>&1;
+echo "[-] git checkout ${branch}"
+if ! doas -u _portzap "${git}" \
+                       checkout -t \
+                       origin/"${branch}" \
+                       > /dev/null 2>&1; then
+    echo "[-] 'git checkout' exited with an error"
+    exit "${?}"
+else
     echo "[-] Done"
+fi

libexec/portzap/portzap-pull

@@ -22,7 +22,7 @@ change_branch()
     if ! doas -u _portzap "${git}" checkout "${branch}" > /dev/null 2>&1 ||
          doas -u _portzap "${git}" checkout -t "${remote}"/"${branch}" > /dev/null 2>&1; then
         echo "[-] 'git checkout' exited with an error"
-        exit 1
+        exit "${?}"
     else
         echo "[-] Done"
     fi