We are going to revert the tcsh exit value behaviour to the CSH default (as it used to work in tcsh for many years/decades). There will be $tcsh_posix_status variable available to opt-in the POSIX-like behaviour (as in bash, ksh, etc.).
$ false | true
$ echo $?
1
$ set tcsh_posix_status
$ false | true
$ echo $?
0
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
http://rhn.redhat.com/errata/RHBA-2013-0052.html