BitKeeper open-sourced

[Kamil Rytarowski <n54%gmx.com@localhost>]

BitKeeper is now released as APL-2.0. https://www.bitkeeper.org/

From the webpage:

BitKeeper is the original distributed source management system. Now
available as Open Source under the Apache 2.0 License.

BitKeeper is a fast, enterprise-ready, distributed SCM that scales up to
very large projects and down to tiny ones.

Features:
 -    Simple: An easy to use command line interface.
 -    Scalable: Nested Repositories are submodules done right! Version
      control collections of repositories.
 -    Flexible: Hybrid mode for binary files that uses a cloud of
      server for binaries instead of bloating the source repositories.
 -    Accurate: Tracking of file operations like creates, deletes, and
      renames.
 -    Safe: All file accesses validate checksums for integrity. All
      file writes include redundancy for error correction.
 -    Dependable: Highly accurate auto-merge that uses the whole
      history to resolve conflicts. Most other systems use variations
      of diff3.
 -    Discernable: Source annotations instantly available.
 -    Fast: High performance and scales to very large repositories.
 -    Free: Licensed under the Apache Version 2 license



It matches the requirements of David Holland from "preliminary version
control requirements" [1], except branching -- as branches are handled
as separate clones. According to the upstream developers it should work
well for releng.

There is a fallback for restricted environment to pull the changes from
a remote repository and more or less (according to my understanding)
apply binary diff from upstream tarball to the checkout (according to
upstream show work pretty fine with 64MB RAM).

Performance comparisons with git are pretty promising, p. 5:
http://www.mcvoy.com/lm/bkdocs/productline.pdf

BitKeeper currently depends on PCRE and TCL/TK, but at least the TCL/TK
requirement is going to be detached and bitkeeper-base-like package will
depend on C. There are more dependencies bundled in and they are in
process of unloading.

The code is NetBSD friendly, upstream used our source-code (notably
stdio from libc) for portability reasons.

There is strong upstream commercial support for BK and the product isn't
going anywhere.

I hope It shouldn't be too difficult to get help from upstream with
proper CVS->BK conversion.

[1] http://mail-index.netbsd.org/tech-repository/2008/07/26/msg000003.html