Version strings with the same prefix, e.g. "1.0" and "1.0~pre", or even
"1.0" and "1.0.1" were considered equal. This is a regression in the C
autoupdater rewrite.
This new version of the autoupdater is implemented in C instead of Lua,
allowing us to interface with libuclient (HTTP downloads) and libecdsautil
(signature checks) directly instead of spawning external processes,
saving RAM and making error handling more robust.
[Matthias Schiffer: add commit message]