See URL. We're short on IDs in the low range with the range below 500 almost completely filled. On the medium to long term, this issue should be fixed, presumably by making it configurable. (For example, use UID_MIN and UID_MAX from /etc/login.defs to determine what are user accounts?)
From #gentoo-qa: <floppym> Most of the issues I found are greater restrictions placed on system users. We could probably get away with running services as non-system users. <floppym> I'm thinking we follow this sequence: 1. Open up a wider range of ids < 1000. 2. Expand to a new range somewhere above 60000. 3. Patch systemd if #2 causes real problems reported by users. <ulm> yeah, that wfm