Properly count newlines appearing at the end of templates after rendering

Fixes #4633

lib/ansible/utils/string_functions.py

@@ -5,3 +5,11 @@ def isprintable(instring):
     isprintable = set(instring).issubset(printset)
     return isprintable
 
+def count_newlines_from_end(str):
+    i = len(str)
+    while i > 0:
+        if str[i-1] != '\n':
+            break
+        i -= 1
+    return len(str) - i
+