change of zfs mount options?

[Greg Troxel <gdt%lexort.com@localhost>]

I've had a netbsd-10 amdt64 machine for a long time, most data on zfs,
xen dom0.  I recently upgraded it to 11RC4, and found that
pkgsrc/devel/gettext-tools wouldn't build, because pkgsrc was mounted
noexec.

A "zfs set exec=yes" on the dataset resolved this.

I have no memory of this happening before, so I wonder if defaults
changed.

Perhaps this is "fixes for property overrides", part of a big pullup of
zfs fixes (yay!) and it always should have been like that.

Clues appreciated.