removed [[ TEST ]] && action form for if [[ TEST ]]; then action; fi for compatibility

modules/install_mkagent.sh

@@ -25,14 +25,14 @@ install_mkagent()
 
 precheck_install_mkagent()
 {
-    [[ -n $MKVERSION ]] && (
+    if [[ -n $MKVERSION ]]; then
         prnt E "Undeclared check_mk version of the agent to install."
         die 162
-    )
-    [[ -n $MK_SERVER ]] && (
+    fi
+    if [[ -n $MK_SERVER ]]; then
         prnt E "Undeclared check_mk server."
         die 162
-    )
+    fi
 }
 
 export -f install_mkagent