Bug#635697: pbuilder-satisfydepends --internal-chrootexec should be documented

[Ian Jackson]

Package: pbuilder
Version: 0.199+nmu1

I appreciate that this option was originally intended for internal use
by other parts of pbuilder.

However, pbuilder is one of very few tools which are able to honour
and satisfy externally-specified dependencies (ie dependency strings
provided by the tool's caller, rather than in the form of a package in
some archive mentioned in apt's sources.list).  Indeed the pbuilder
package has now collected implementations of several different
approaches to solving this problem.

So I think it would be useful to try to build on this starting point.
Having other programs run /usr/lib/pbuilder-satisfydepends[-something]
seems like a not unreasonable interface.

But there is one little thing missing: pbuilder-satisfydepends
supports a mechanism for doing the actual installation in an
environment other than the caller's - but the published option
"--chroot" only works for switching to chroots.

The unpublished option --internal-chrootexec is more powerful but
undocumented.  It would be nice to have it listed in the usage output,
with of course the implicit promise that it wouldn't be arbitrarily
removed or changed.

FYI I'm already using it so if renaming is thought to be a good idea,
it would be nice if the existing name could be kept as an alias.

Thanks,
Ian.