[3.5.0 regression] Rsync fails to open filter list supplied from shell process substitution

[whitslack]

$ rsync --version | head -n1
rsync  version 3.4.4  protocol version 32

$ rsync --filter='.-s '<(:) /tmp/ /tmp/
skipping directory .

$ rsync --version | head -n1
rsync  version 3.5.0  protocol version 32

$ rsync --filter='.-s '<(:) /tmp/ /tmp/
rsync: [client] failed to open exclude file /dev/fd/63: No such file or directory (2)
rsync error: error in file IO (code 11) at exclude.c(1719) [client=3.5.0]

This is, of course, a trivialized minimal reproducer. In actual practice the process executed by the process substitution would output a list of paths to exclude.

[seks99x]

I traced the ENOENT issue to the new ona_open() function. The problem happens because ona_open() manually resolves symlinks using readlinkat(). When it hits a Bash process substitution like /dev/fd/63, readlinkat() returns the kernel pseudo-path "pipe:[XXXXXXX]". The function then treats this string as a literal relative filename and passes it to the next kernel syscall, which naturally rejects it with ENOENT.