Fossil is a distributed software control system that includes a
whole palette of useful companion software: for example, bug
tracking and a wiki.

It allows autosyncing with an upstream before a commit.  fossil is
a single standalone executable, using bandwidth efficient transfers
over HTTP. It includes its own HTTP server for providing the
repository, if needed.

The repository is kept in a sqlite database, only updated with
atomic commits, which can be checked by fossil itself for consistency.

Homepage:
http://www.fossil-scm.org/
