just: shellcheck setup hook

pkgs/by-name/ju/just/setup-hook.sh

@@ -1,3 +1,5 @@
+# shellcheck shell=bash
+
 justBuildPhase() {
     runHook preBuild
 
@@ -15,7 +17,7 @@ justCheckPhase() {
 
     if [ -z "${checkTarget:-}" ]; then
         if just -n test >/dev/null 2>&1; then
-            checkTarget=test
+            checkTarget="test"
         fi
     fi
 
@@ -44,14 +46,14 @@ justInstallPhase() {
     runHook postInstall
 }
 
-if [ -z "${dontUseJustBuild-}" -a -z "${buildPhase-}" ]; then
+if [ -z "${dontUseJustBuild-}" ] && [ -z "${buildPhase-}" ]; then
     buildPhase=justBuildPhase
 fi
 
-if [ -z "${dontUseJustCheck-}" -a -z "${checkPhase-}" ]; then
+if [ -z "${dontUseJustCheck-}" ] && [ -z "${checkPhase-}" ]; then
     checkPhase=justCheckPhase
 fi
 
-if [ -z "${dontUseJustInstall-}" -a -z "${installPhase-}" ]; then
+if [ -z "${dontUseJustInstall-}" ] && [ -z "${installPhase-}" ]; then
     installPhase=justInstallPhase
 fi