* Alexey I. Froloff <raorn@> [090421 13:39]:
> apt почему-то предпочитает вытаскивать старый ruby-module-erb
> вместо нового ruby-stdlibs (который Provides/Obsoletes).
В чрут установлены ruby и libruby версии 1.9.1-alt1.20090412.

$ ./aptbox/apt-get -oDebug::PkgProblemResolver=true -oDebug::PkgMarkInstall=true install ruby-module-etc                                                                                                             
Reading Package Lists... Done
Building Dependency Tree... Done
MI2a: mark ruby-module-etc
Starting
Starting 2
Investigating ruby-module-etc
Package ruby-module-etc has broken dep on libruby
  Considering libruby 4 as a solution to ruby-module-etc 9999
Package ruby-module-etc has broken dep on libruby.so.1.8
  Considering libruby 4 as a solution to ruby-module-etc 9999
Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.

Since you only requested a single operation it is extremely likely that
the package is simply not installable and a bug report against
that package should be filed.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
  ruby-module-etc: Depends: libruby (= 1.8.7-alt7)
                   Depends: libruby.so.1.8
E: Broken packages

$ ./aptbox/apt-get -oDebug::PkgProblemResolver=true -oDebug::PkgMarkInstall=true install ruby-module-etc=1.9.1-alt1.20090412
Reading Package Lists... Done
Building Dependency Tree... Done
MI2a: mark ruby-stdlibs
MI2a:  target libcrypto.so.7
MI2a:   mark libssl7
MI2a:    target ca-certificates
MI2a:     mark ca-certificates
MI2a:    target libk5crypto.so.3(k5crypto_3_MIT)
MI2a:     mark libkrb5
MI2a:      target libkeyutils.so.1(KEYUTILS_0.3)
MI2a:       mark libkeyutils
MI2a:  target libgdbm.so.3
MI2a:   mark libgdbm
MI2a:  target ruby(tcltklib) AMB
MI2b: mark ruby-stdlibs
MI2b:  target ruby(tcltklib) AMB
MI2c: mark ruby-stdlibs
MI2c:  target ruby(tcltklib)
MI2c:   mark ruby-stdlibs-tk
MI2c:    target libtcl8.5.so
MI2c:     mark libtcl
MI2c:    target libtk8.5.so
MI2c:     mark libtk
MI2c:      target libX11.so.6
MI2c:       mark libX11
MI2c:        target libX11-locales
MI2c:         mark libX11-locales
MI2c:        target libxcb.so.1
MI2c:         mark libxcb
MI2c:          target libXau.so.6
MI2c:           mark libXau
MI2c:          target libXdmcp.so.6
MI2c:           mark libXdmcp
MI2c:      target libXft.so.2
MI2c:       mark libXft
MI2c:        target libXrender.so.1
MI2c:         mark libXrender
MI2c:        target libfontconfig.so.1
MI2c:         mark fontconfig
MI2c:          target libexpat.so.1
MI2c:           mark libexpat
MI2c:          target libfreetype.so.6
MI2c:           mark libfreetype
Starting
Starting 2
Done
The following extra packages will be installed:
  ca-certificates fontconfig libX11 libX11-locales libXau libXdmcp libXft libXrender libexpat libfreetype libgdbm libkeyutils
  libkrb5 libssl7 libtcl libtk libxcb ruby-stdlibs ruby-stdlibs-tk
The following NEW packages will be installed:
  ca-certificates fontconfig libX11 libX11-locales libXau libXdmcp libXft libXrender libexpat libfreetype libgdbm libkeyutils
  libkrb5 libssl7 libtcl libtk libxcb ruby-stdlibs ruby-stdlibs-tk
0 upgraded, 19 newly installed, 0 removed and 0 not upgraded.
Need to get 0B/4996kB of archives.
After unpacking 18.2MB of additional disk space will be used.

Виртуальный пакет просто не выбирается.

-- 
Regards,
Sir Raorn.