Slurping into an empty list yields extra space

[bcarrell]

So, sometimes I have this situation:

()| foo and I slurp in the foo and it ends up being ( foo). This is almost never what I want -- if I'm slurping into an empty list I don't want there to be any spaces. This is easy to fix via i but it's somewhat common enough to be a hint of friction with the extra keypress.

[abo-abo]

Nice remark, thanks. The tests are passing for this change, but some
behavior that's not covered by tests might be different.