File format roadmap needed (was Re: [MERGE] New 'development' format.)

[Matt Nordhoff]

Ian Clatworthy wrote:
> Being able to change formats easily is almost a strength of ours. I say
> "almost" because we're not yet at the point where 'upgrade' can be given
> a shared repository and it will magically do each branch using it. Is
> that enough to make upgrades painless? Possibly not. We might need a
> tool that scans a tree looking for all repositories as well.

'upgrade' could do that, perhaps with an argument.

(It would also make such a tool more helpful if "$tool --pack-0.92"
could upgrade, say, both dirstate-tags -> pack-0.92 and
dirstate-with-subtree -> pack-0.92-subtree at once somehow. I know, it
wouldn't really work easily, because one might want to upgrade
dirstate-tags branches to pack-0.92-subtree too or something. Still an
idea.)
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