Hi myglc2,

I'm sending a patch which implements the following:

--8<---------------cut here---------------start------------->8---
guix build --check /gnu/store/yx1hdcvyc3agv7bwbxm7jv7zlm6ibzqr-manual-database.drv
[...]
Creating manual page database for 62 packages... done in 35.112 s
--8<---------------cut here---------------end--------------->8---

The change improves the message output by the manual-database hook with
the addition is the closing of the message with a "done in x.xxx s".

Thanks to myglc2 for providing a snippet and ideas about how to improve this.

Maxim