Revert "unneded logic"

This reverts commit 18a9c8e.

lib/main.js

@@ -11,8 +11,11 @@ function expandValue (value, processEnv, runningParsed) {
 
   let result = value
   let match
+  const seen = new Set() // self-referential checker
 
   while ((match = regex.exec(result)) !== null) {
+    seen.add(result)
+
     const [template, bracedExpression, unbracedExpression] = match
     const expression = bracedExpression || unbracedExpression
 
@@ -38,12 +41,17 @@ function expandValue (value, processEnv, runningParsed) {
     }
 
     if (value) {
-      result = result.replace(template, value)
+      // self-referential check
+      if (seen.has(value)) {
+        result = result.replace(template, defaultValue)
+      } else {
+        result = result.replace(template, value)
+      }
     } else {
       result = result.replace(template, defaultValue)
     }
 
-    // if the result equaled what was in runningParsed then stop expanding - handle self-referential check as well
+    // if the result equaled what was in process.env and runningParsed then stop expanding
     if (result === runningParsed[key]) {
       break
     }