rsync 3.2.7 hangs when --usermap is used and receiver is not a super-user

[Tomasz Chmielewski]

After upgrading to rsync 3.2.7, the following command hangs forever 
(using "--usermap" causes the hang; without "--usermap" it doesn't 
hang):

rsync -v -p -e --usermap user:user /etc/services user at remote:

It did not hang with rsync 3.2.3.

Not sure if it's intended behaviour? The fine manual says that --usermap 
should be used as a super-user on the receiver, but does not mention 
that it will hang if used as a non-super-user.

Reproducible on Ubuntu 20.04 LTS.


Tomasz Chmielewski