resolved: fix use of ERRNO_IS_DISCONNECT()

resolved: fix use of ERRNO_IS_DISCONNECT()

Given that ERRNO_IS_DISCONNECT() also matches positive values,
make sure this macro is not called with arguments that do not have
errno semantics.

In this case the argument passed to ERRNO_IS_DISCONNECT() is the value
returned by manager_recv() which can legitimately return 1 without errno
semantics, so fix this by moving ERRNO_IS_DISCONNECT() invocation to the
branch where the return value is known to be negative.