As part of SERVER-18376, we need to update the docs (http://docs.mongodb.org/manual/reference/command/buildInfo/) to specify which parts of the results of buildInfo command are stable, and which may change.

The following fields in buildInfo are stable and won't change.

• version
• gitVersion
• versionArray
• bits
• debug
• maxBsonObjectSize
• storageEngines
• javascriptEngine

All other fields are for internal/debugging use and may change between release series.

The sysInfo field is deprecated, will only report "deprecated" in 3.2, and may be removed in future versions.