Because Mojang’s update infrastructure in 2010 was rudimentary, these small "sub-versions" were often overwritten on the download servers by the next major release (Beta 1.0) on December 20, 2010. 2. The Preservation Gap
It was primarily a bug-fix update following the massive "Halloween Update" (v1.2.0), which introduced the Nether. minecraft alpha 1.2.6-01