Blender Version
Broken: 2.78c release for example
Worked: (optional)
2.78 release for example

Short description of error
For instance in 2.78c, The Help --> Python API Reference link refers to
https://docs.blender.org/api/blender_python_api_2_78c_release
which does not exist.
https://docs.blender.org/api/blender_python_api_2_78_release
works, instead. (so it works in initial releases, but not in x.xxa, b, c... releases)

Exact steps for others to reproduce the error
click on Info > Help > Python API Reference

I'd consider it as not too serious, but wanted to report it anyway.