Ignore new commits for git submodule

Just run:

$ git submodule update

This will revert the submodule the to old commit (specified in parent-repo), without updating the parent-repo with the latest version of the submodule.

To include another repository, that needn't be tracked in its super-repo, try this:

$ cd /path/to/master/$ rm -rf book$ git clone https://user@bitbucket.org/user/repo.git book$ git add book$ echo "book" >> .gitignore

Then commit.

As stated in the linked git submodule pitfalls article:

... the only linkage between the parent and the submodule is [the] recorded value of the submodule’s checked-out SHA which is stored in the parent’s commits.

That means that a submodule is not saved by its checked-out branch or tag, but always by a specific commit; that commit (SHA) is saved into the super-repo (the one containing the submodule) like a normal text file (it's marked as such a reference, of course).

When you check out a different commit in the submodule or make a new commit in it, the super-repo will see that its checked out SHA has changed. That's when you get the modified (new commits) line from git status.

To eliminate that, you can either:

• git submodule update, which will reset the submodule to the commit currently saved in the super-repo (for details see the git submodule manpage; or
• git add book && git commit to save the new SHA into the super-repo.

As mentioned in the comments, consider abandoning the book submodule: clone it inside the super-repo, if tracking of its state as part of the super-repo is not necessary.

There are two kinds of change notices you can suppress (from git 1.7.2).

The first is untracked content which happens when you make changes to your submodule but have not yet committed those. The parent repository notices these and git status reports it accordingly:

modified: book (untracked content)

You can suppress these with :

[submodule "book"]    path = modules/media    url = https://user@bitbucket.org/user/repo.git    ignore = dirty

However, once you commit those changes, the parent repository will once again take notice and report them accordingly:

modified:   book (new commits)

If you want to suppress these too, you need to ignore all changes

[submodule "book"]    path = book    url = https://user@bitbucket.org/user/repo.git    ignore = all