- People almost always push to a single place, and many people would push a single branch they are currently on. The default behaviour of "git push" (that does not say which branches to push out to where on the command line) has been updated to better support this mode of working (as opposed to working on making all branches they are going to publish ready and then push all of them in one go). The old default of pushing out all the matching branches is available by setting the push.default configuration variable to matching.
- Even though "git commit -a" can be run from any subdirectory to commit changes to all the tracked paths in the working tree, "git add -u" and "git add -A" (without specifying any path on the command line) used to operate only inside the current directory. This inconsistency bothered many people, and these commands have been updated to operate on all modified (for "-u") or all (for "-A") paths. Use "git add -u ." and "git add -A ." to restrict the command to the current directory.
- "git add path" is now the same as "git add -A path" now, so that "git add directory/" will notice paths you removed from the directory and record the removal. In older versions of Git, it used to ignore removals. You can say "git add --ignore-removal path" to add only added or modified paths, if you really want to.
Some of the readers may remember that we didn't give users a very good transition experience when we introduced a backward incompatible change in Git 1.6.0. We used to install all the "git-cmd"s in the same directory as "git" itself and people were used to that "git commit" and "git-commit" can be used interchangeably before that release. Then we stopped installing what does not have to be on user's $PATH at that release, which is a change that breaks people's finger-memory and existing scripts. All we did to prepare users for that change was to warn about it in release notes since Git 1.5.4 and it was apparently not enough. Many people were unhappy.
In retrospect, perhaps we could have done better by adding code to somehow detect when "git-cmd" is invoked as the top-level command and warn that such usage would break in future versions to train users to use "git cmd" form way before releasing the version that actually delivered the change.
This time around, we have been trying to be a lot more careful. For the past handful of releases, we have added extra code to detect cases where exiting versions of Git and the upcoming Git 2.0 will behave differently and to warn about the upcoming change. As the result, the actual difference between Git 1.9 and Git 2.0 is mostly "flipping the default" for these changes.