backwards compatibility, was Re: [PATCH v1 1/3] Introduce config variable "diff.primer"

Hi,

On Sun, 25 Jan 2009, Jeff King wrote:

  1. Sometimes we blur the line of plumbing and porcelain, where
     functionality is available only through plumbing. For example,
     gitweb until recently called "git diff" because there is no other
     way to diff two arbitrary blobs. But the solution there is, I
     think, to make that functionality available through plumbing. Not
     to disallow enhancements to porcelain.

Just a reminder: we are very conservative when it comes to breaking 
backwards compatibility.  For example, people running (but not upgrading) 
gitweb who want to upgrade Git may rightfully expect their setups not to 
be broken for a long time, if ever.

So your mentioning gitweb using "git diff" precludes all kind of cute 
games, methinks.

And please no "anybody who would do this and that would be nuts" excuses: 
if you want to change something fundamental like this, _you_ have to 
defend it.

It is not acceptable to just shout out what you want and expect those 
affected negatively to do the impact analysis for you.

Ciao,
Dscho