eventsignups: no confirmation-email sent after manual accept

Created by: niccantieni

It seems like no confirmation-email is sent after a user was manually accepted to an event (i.e. the mode is manual, not fcfs). The issue was noticed on the event 62b32980547064b604c46645, link.

I signed up and was placed on the waiting list immediately (which is correct, since the manual mode was selected),. Then, at some point in the last days I was manually accepted, but never got a confirmation email.

It seems like it was intended to add this confirmation email in PR #159, but I cannot tell whether the code is actually correct. Maybe the code only works if one is promoted from a waiting list which exists because the event is full (and not because it is a manual event)? Some of the relevant code is here.

Possible other issue: maybe the request sent by the admin-tool is wrong, i.e. when the "accept"-button in the waiting-list table is pressed, the request is missing some values? Maybe something goes wrong with the explicit accept: true required by the API, which can only be set by the API itself or by moderators (according to the documentation). The request is assembled here.

I am going to look into this some more, but any pointers as to what may be wrong are much appreciated.