[chousuke]

Branches don't really "disappear" in git, though. You're probably already aware of this, but for everyone not familiar with how git works:

Named branches in git are just moving references to commits. If you delete the pointer, the branch doesn't cease to exist, as it is present in the repository 'tree'. If you know the commit that was the head of the branch, you can easily create a new reference to it. The branch might eventually get garbage-collected if there is no other named ref that depends on it.

For example, if you merge "feature-foo" to "master" and then delete "feature-foo", the name is gone. However, the branch is still there (clearly visible in git-gui), and will not be garbage-collected because "master" depends on it.

The "problem" with hg in my opinion is that it attaches more meaning to the name of the branch than is necessary.

Of course, git also allows you to destroy commits, and destroying ones that you have shared with other repositories may lead to complaints from others developers. But that's a social issue; git will not (and never should) dictate what you do with your commits, it just tracks them.