Language prefix missing from expiration path

Using language prefix on all nodes, e.g. http://example.com/en/my/path (let's say it's node/123).
On the Cache Expiration tab of the given node all checkboxes are on.

On edit and save of a page the page is NOT expired from external cache (Varnish, with Purge).

The Watchdog message contains (among others) these URLs:
URL: node/123
Wildcard: false
Expired object: node
--------
URL: my/path
Wildcard: false
Expired object: node

I then tried manual expiration via command line and found:
curl -X PURGE -H "Host: example.com" http://127.0.0.1:80/my/path -> cache NOT cleared
curl -X PURGE -H "Host: example.com" http://127.0.0.1:80/en/my/path -> cache CLEARED

So it seems to me that there is a problem with including the language prefix in the expired URLs.

NB "Include base URL in expires" is UNchecked because of the help text "Enabling this setting when Varnish (link is external) or Acquia Purge (link is external) modules are used as a cache backend is not recommended."
So as I use Varnish module, I should keep it unchecked, right?