Bug#1022855: cron script floods system mail box with "which: this version of which is deprecated, use command -v instead"

[M. Zhou]

Package: zfs-auto-snapshot
Version: 1.2.4-2
Severity: important
Tags: +patch

Dear maintainer,

After the deprecation of which, that command now creates lots of noise
and floods the system mail box. A simple fix is to replace the command.