cargo vendor fails with "found duplicate version of package `encoded-words v0.2.0`"

[dotlambda]

Running cargo vendor on 50e53f2c8293314ca535711ebb109a050e8ea133 fails with

error: failed to sync

Caused by:
  found duplicate version of package `encoded-words v0.2.0` vendored from two sources:

  	source 1: registry `crates-io`
  	source 2: https://github.com/async-email/encoded-words?branch=master#d55366b3

This prevents me from updating libdeltachat in Nixpkgs. See https://github.com/NixOS/nixpkgs/issues/30742.

[Simon-Laux]

the flatpak also has problems with this: https://github.com/flathub/chat.delta.desktop/pull/95