Thank you for taking the time to report this bug and helping to make Ubuntu better.
This is interesting and I appreciate your investigation! I wonder though if there's a third outcome here - that it's not a bug because the glibc implementation of lchmod() requires /proc to be mounted, and if you don't have /proc mounted then by that definition you have a broken system and lchmod() is not expected to work, so rsync won't work, as a design decision of upstream glibc.
I'm not claiming that this is the case, just that it's another case to consider.
Thank you for taking the time to report this bug and helping to make Ubuntu better.
This is interesting and I appreciate your investigation! I wonder though if there's a third outcome here - that it's not a bug because the glibc implementation of lchmod() requires /proc to be mounted, and if you don't have /proc mounted then by that definition you have a broken system and lchmod() is not expected to work, so rsync won't work, as a design decision of upstream glibc.
I'm not claiming that this is the case, just that it's another case to consider.