Version Control System + Integration Server

Rules:

• Version Control System should deny commits if the integration server is down. This could be done via hooks (that's the rare case, when the usage of VCS hooks is somewhat justified).
• OR Integration server should process incoming commits one by one.
• Optionally, commit should be denied, if it breaks the build (I believe integration server from the JetBrains does this)

This will ensure that we do not have to waste time trying figure out which commit did break the build.

Obviously, the integration build should be lightning-fast.