After cd'ing to a working copy:

$ { svn info ; echo "Exit status: $?" >&2 ; } > /dev/null
Exit status: 0

but

$ { svn info ; echo "Exit status: $?" >&2 ; } | true
Exit status: 1

This is actually a broken pipe, so that the exit status should be
128+SIGPIPE in order to be able to differentiate this error[*] from
other errors.

[*] In some contexts, the broken pipe could be expected, thus be
ignored by scripts.