localhost ~ # emerge portage --pretend
These are the packages that would be merged, in order:
Calculating dependencies... done!
[ebuild U ] dev-python/pycrypto-2.0.1-r6 [2.0.1-r5]
[ebuild U ] sys-apps/portage-2.1.4.4 [2.1.3.4-r1] LINGUAS="-pl*"
*** Portage will stop merging at this point and reload itself,
then resume the merge.
[ebuild U ] app-shells/bash-3.2_p33 [3.2_p15-r1] USE="-plugins%"
[blocks B ] <sys-apps/portage-2.1.4_rc1 (is blocking app-shells/bash-3.2_p33)
localhost ~ # emerge -u sys-apps/portage-2.1.4_rc1
Calculating dependencies -
!!! 'sys-apps/portage-2.1.4_rc1' is not a valid package atom.
!!! Please check ebuild(5) for full details.
!!! (Did you specify a version but forget to prefix with '='?)
localhost ~ # emerge -u sys-apps/portage
Calculating dependencies... done!
!!! Error: the <sys-apps/portage-2.1.4_rc1 package conflicts with another package;
!!! the two packages cannot be installed on the same system together.
!!! Please use 'emerge --pretend' to determine blockers.
For more information about Blocked Packages, please refer to the following
section of the Gentoo Linux x86 Handbook (architecture is irrelevant):
http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?full=1#blocked