Similar to Bug #29614, it would be nice to allow TpBaseClient to wait for more features. The referenced branch implements this.
We designed TpAccountChannelRequest to allow this to be passed through, too; I haven't yet added the necessary boilerplate (it'd be similar to the new API on TpBaseClient), but if people like the look of this work, I could.
The patch looks good but see my comments on bug #29614.
Will be fixed as part of Bug #29614, then.
*** This bug has been marked as a duplicate of bug 29614 ***