Re: [PATCH v6 0/8] push: update remote tags only with force

On Wed, Jan 16, 2013 at 11:43 AM, Jeff King [off-list ref] wrote:

I think that is a reasonable rule that could be applied across all parts
of the namespace hierarchy. And it could be applied by the client,
because all you need to know is whether ref->old_sha1 is reachable from
ref->new_sha1.

is_forwardable() did solve a UI issue.  Previously all instances where
old is not reachable by new were assumed to be addressable with a
merge.  is_forwardable() attempted to determine if the concept of
forwarding made sense given the inputs.  For example, if old is a blob
it is useless to suggest merging it.

Chris