upload.py should not always fail (esp8266#8608)

esp8266@0778980#r76344981
thx @jjsuwa-sys3175

Author: mcspr

tools/upload.py

@@ -70,5 +70,5 @@
 finally:
     if erase_file:
         os.remove(erase_file)
-    if sys.exc_info:
+    if any(sys.exc_info()):
         sys.exit(2)