fix(pkg): correctly extract tarballs

[rgrinberg]

trafficstars

Previously, we'd extract sources as [source/$basename-of-tar]. We should instead extract the sources into [source/] directly.

Signed-off-by: Rudi Grinberg [email protected]

[rgrinberg]

@gridbugs this demonstrates the fix in the e2e test

[rgrinberg]

@Leonidas-from-XIV should be ready now

[gridbugs]

I just tried out this change locally and it seems to introduce errors during dune build:

Error:
rename(/run/user/1000/dir_d4279f_download/ppx_derivers-1.2.1): Invalid cross-device link
-> required by
   _build/_fetch/checksum/md5=5dc2bf130c1db3c731fe0fffc5648b41/dir
-> required by _build/_private/default/.pkg/ppx_derivers/source
-> required by _build/_private/default/.pkg/ppx_derivers/target/cookie
-> required by - package ppxlib
-> required by - package ppx_cold
-> required by - package ppx_base
-> required by - package base_quickcheck
-> required by - package ppx_jane
-> required by - package abstract_algebra

for a bunch of packages. This was from building an empty package dependent on incr_map on nixos.

[rgrinberg]

Sigh. The temp directory has to exist in the build directory I suppose.