I have checked adduser and useradd commands too, and I think it should have the same default shell in both.
It's weird to have different values.
By the way, to reply to unggnu, the default is set to /bin/sh because this should be just a link to the default shell used on the system. It was ok then, when Ubuntu was still using bash as the target of /bin/sh, but from edgy, it has changed to dash instead of bash (to reduce the memory footprint if I remember correctly).
I have checked adduser and useradd commands too, and I think it should have the same default shell in both.
It's weird to have different values.
By the way, to reply to unggnu, the default is set to /bin/sh because this should be just a link to the default shell used on the system. It was ok then, when Ubuntu was still using bash as the target of /bin/sh, but from edgy, it has changed to dash instead of bash (to reduce the memory footprint if I remember correctly).