vimcore or

#> emerge =vim-core-7.3.600
Calculating dependencies... done!
[ebuild     U  ] app-editors/vim-core-7.3.600 [7.3.537]

!!! Multiple package instances within a single package slot have been pulled
!!! into the dependency graph, resulting in a slot conflict:

app-editors/vim-core:0

  (app-editors/vim-core-7.3.600::gentoo, ebuild scheduled for merge) pulled in by
    =vim-core-7.3.600

  (app-editors/vim-core-7.3.537::gentoo, installed) pulled in by
    ~app-editors/vim-core-7.3.537 required by (app-editors/vim-7.3.537::gentoo, installed)
    (and 1 more with the same problem)