Objections to using Git as a VCS, per discussion at  http://irclog.perlgeek.de/parrot/2009-09-17#i_1510436 .

• Integration with trac.
• Demonstrate that git actually is better at resolving the merging conflicts we hit in real usage.
• Source code browsing tools. (including revision browsing)
• Down-time and retraining time for developers.
• Safety of the core source (limiting the damage possible accidentally or by new committers)
  • (with git it's possible to make changes that destroy the history of the repository)