I find that g-cran and portage master branches are incompatible.

Any attempt to merge or update a dev-R ebuild fails:

An example of an update attempt, where the distfile is already
downloaded (copied over from a cran mirror):

:; emerge -v dev-R/sp

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild     U  ] dev-R/sp-0.9.80 [0.9.78] USE="doc" 0 kB [1]

Total: 1 package (1 upgrade), Size of downloads: 0 kB
Portage tree and overlays:
 [0] /usr/portage
 [1] /usr/local/portage/Overlays/g-cran


>>> Emerging (1 of 1) dev-R/sp-0.9.80 from g-cran
!!! Fetched file: sp_0.9-80.tar.gz VERIFY FAILED!
!!! Reason: Insufficient data for checksum verification
!!! Got:      
!!! Expected: MD5 RMD160 SHA1 SHA256
 * Fetch failed for 'dev-R/sp-0.9.80', Log file:
 *  '/var/log/portage/build/dev-R/sp-0.9.80:20110416-221838.log'

>>> Failed to emerge dev-R/sp-0.9.80, Log file:

>>>  '/var/log/portage/build/dev-R/sp-0.9.80:20110416-221838.log'

 * Messages for package dev-R/sp-0.9.80:

 * Fetch failed for 'dev-R/sp-0.9.80', Log file:
 *  '/var/log/portage/build/dev-R/sp-0.9.80:20110416-221838.log'


And here is one where the distfile still needs downloading:

:; emerge -v dev-R/AIM

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild  N     ] dev-R/AIM-1.01  USE="doc" 0 kB [1]

Total: 1 package (1 new), Size of downloads: 0 kB
Portage tree and overlays:
 [0] /usr/portage
 [1] /usr/local/portage/Overlays/g-cran


>>> Emerging (1 of 1) dev-R/AIM-1.01 from g-cran
!!! Fetched file: AIM_1.01.tar.gz VERIFY FAILED!
!!! Reason: Insufficient data for checksum verification
!!! Got:      
!!! Expected: MD5 RMD160 SHA1 SHA256
 * Fetch failed for 'dev-R/AIM-1.01', Log file:
 *  '/var/log/portage/build/dev-R/AIM-1.01:20110416-221950.log'

>>> Failed to emerge dev-R/AIM-1.01, Log file:

>>>  '/var/log/portage/build/dev-R/AIM-1.01:20110416-221950.log'

 * Messages for package dev-R/AIM-1.01:

 * Fetch failed for 'dev-R/AIM-1.01', Log file:
 *  '/var/log/portage/build/dev-R/AIM-1.01:20110416-221950.log'


Which is essentially the same error.

Re-merging g-cran does not help.

If it matters:

:; eselect python list
Available Python interpreters:
  [1]   python2.5
  [2]   python2.6
  [3]   python2.7 *
  [4]   python3.1

Of course, the fact that the Manifest files were never real was always a
bug.  I wanted to write a replacement before reporting this, but the tuits
have been too pointy....

-JimC
-- 
James Cloos <cloos@...>         OpenPGP: 1024D/ED7DAEA6