[PATCH 4 of 4 V2] import: use ui.allowemptycommit to allow empty commits

[Durham Goode]

On 5/11/15 8:29 PM, Durham Goode wrote:
> # HG changeset patch
> # User Durham Goode <durham at fb.com>
> # Date 1431400541 25200
> #      Mon May 11 20:15:41 2015 -0700
> # Node ID e9ae79f97326eb5ee5d9415ba997cd5401fcf57c
> # Parent  17cc5e344169e24cf5af7900f3b3bbd00993f24b
> import: use ui.allowemptycommit to allow empty commits
>
> Previously import used force=partial to allow empty commits to be made. Let's
> switch it to using the new ui.allowemptycommit option.
>
> This is the last known use of force for allowing empty commits, so let's remove
> it from the allowemptycommits condition.
>
I don't actually think we should take patches 3 and 4 in this series.  
We can't actually get rid of the force flag entirely because it does a 
bunch of other things, so these two patches just introduce some funky 
config backup/set/restore logic in exchange for deleting 'force' from a 
single condition.

I only include them because it was mentioned that ui.allowemptycommit 
would only be worth it if the other places that require empty commits 
used the same code path.