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

Calculating dependencies ... done!
Dependency resolution took 1.49 s (backtrack: 0/20).

[ebuild     UD ] sys-libs/zlib-1.3.1-r1:0/1::gentoo [1.3.2-r1:0/1::gentoo] USE="-minizip -static-libs -verify-sig" 1276 KiB

Total: 1 package (1 downgrade), Size of downloads: 1276 KiB