[OTA] Fix "Error response from device" if OK response comes to early (#1695)

Because TCP is stream-based, an earlier read can 'take away' the "OK" response
from the device, so that a later read doesn't get the message.

tools/espota.py

@@ -179,6 +179,7 @@ def serve(remoteAddr, localAddr, remotePort, localPort, password, filename, comm
       try:
         connection.sendall(chunk)
         res = connection.recv(10)
+        lastResponseContainedOK = 'OK' in res.decode()
       except:
         sys.stderr.write('\n')
         logging.error('Error Uploading')
@@ -187,6 +188,13 @@ def serve(remoteAddr, localAddr, remotePort, localPort, password, filename, comm
         sock.close()
         return 1
 
+    if lastResponseContainedOK:
+      logging.info('Success')
+      connection.close()
+      f.close()
+      sock.close()
+      return 0
+
     sys.stderr.write('\n')
     logging.info('Waiting for result...')
     try: