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

Calculating dependencies ... done!
Dependency resolution took 1.54 s (backtrack: 0/20).

[ebuild     UD ] app-text/build-docbook-catalog-2.3-r1::gentoo [2.4::gentoo] 5 KiB

Total: 1 package (1 downgrade), Size of downloads: 5 KiB