Why not hard link for hg copy?

[Neal Becker]

Matt Mackall wrote:

> On Tue, 2009-06-09 at 10:21 -0400, Neal Becker wrote:
>> Subject says it all.
> 
> Other programs cannot be trusted to do the right thing with hardlinks.
> Otherwise, normal cp would use hardlinks by default as well.
> 

I suppose this actually brings up the question of just what are the 
semantics of hg copy supposed to be?  I was assuming that this marks the 
file as _forever_ being a duplicate.  In this model, you would not be 
allowed to check in a change to file A that is different than file B.  You 
would have to tell hg they are no longer copies.

If this is not the semantics, then it's not obvious to me what the purpose 
of hg copy is.