bug: qTox receiving FT hanges when friend status changes

[Green-Sky]

Brief Description

When receiving a file with qTox and the sender also changes the status (eg. Online to Busy), the sender sees a file transfer cancel, and the receiving qTox shows a stale FT with "resuming".

OS: Linux ubuntu 20.04 LTS
qTox version: nightly-appimage
Commit hash: either b728849(latest as of this issue) or 1 before that, whatever the nightly tag was
toxcore: 0.2.18
Qt: 5.9.5
…

Reproducible: Always (/ Almost Always ?)

Steps to reproduce

1. start sending a file to a qTox using friend
2. change status real quick (eg. Online -> Busy)
3. the sender now sees the FT as canceled and the receiving qTox shows as resuming

Observed Behavior

see above

Expected Behavior

FT should not be influenced by a status change

Additional Info

---

example log:

[13:53:35.155 UTC] core/corefile.cpp:148 : Debug: "sendFile: Created file sender 0 with friend 1"
[13:53:35.322 UTC] core/corefile.cpp:460 : Debug: onFileControlCallback: Received resume for file  1 : 0
[13:53:36.856 UTC] persistence/profile.cpp:501 : Debug: Saving tox save to  "/home/xxx/.config/tox/XXX.tox"
[13:53:37.023 UTC] core/corefile.cpp:447 : Debug: File transfer 1 : 0 cancelled by friend