Comment 2 for bug 1055551

The output "ps:display.c:59: please report this bug" is from procps-ng, so I'd suspect it's rather an issue in procps-ng than in zsh.

The difference to bash is possible caused by differences about when subshells are spawned and when not -- an area where the POSIX specification is ambiguous and hence different behaviour is to be expected.

I can also reproduce this issue with zsh from Debian Experimental (on which Quantal's zsh package is based upon) and with zsh in Debian Unstable and Testing (on which Precise's zsh package is based upon). In those case procps 1:3.3.3-2 where used. But Precise has 1:3.2.8-11ubuntu6, so I guess the difference is rather the procps than the zsh version. Reassigning.