E.memoryArea not working on ESP8266 (due to char-iterator ?)

One more test.
This time the SHA1 was copied to flash without function body.
All variables have been set to undefined at the end of source.
2 more global variables are defined, one for input data, one for the result.

• sent to board with minification free:1330
  
• checked memory some seconds later free:1347
  
• called test function free:1286, duration 500ms
  
• checked memory some seconds later free:1292
  
• called test function several times, no change in free memory