patches-applied historical imports (usd import)

[Ian Jackson]

Nish Aravamudan writes ("patches-applied historical imports (usd import)"):
> 1) Some source packages (bouncycastle, php7.0 are the ones I can think
> of off the top of my head) upstream tarballs contain .gitattributes

I investigted this.  After looking at the docs and playing about, I
concluded that the only sane approach is to record as the actual tree
object (in the git history) the contents of the Debian source package.
Otherwise it will become impossible to represent certain source
packages and all sorts of unanticipated madness could occur.

So I'm currently testing an enhancement to dgit which causes it to
 * unconditionally suprress transforming gitattributes when working
   behind the scenes to import a .dsc
 * by default, configure suppression of these attributes, when
   creating a fresh tree with `dgit clone' (and also in `dgit
   setup-new-tree')

The only other possiblity would be to apply a lossless rename
operation to all .gitattributes, which would be worse.

Ian.