M Gemfile. What does this mean?

I did: git checkout sign-up

And got this:

开发者_如何学运维M   Gemfile
Switched to branch 'sign-up'

What does M Gemfile mean? In the railstutorial.org (end of Ch 7 beginning of Ch 8) it doesn't display that line.

About 30 minutes ago I had to upgrade rake from 0.8.7 to 0.9.2 after I tried downgrading it, but I'm pretty sure it wasn't done cleanly.

It means that the file Gemfile is different from the one that's committed in your git repository. If you made changes (such as the version of rake), then that's what the difference is. To verify the differences and make sure you want to commit it to the repository, you can always do git diff Gemfile.

EDIT: To be clear, M stands for modified. Here's a list of what each status means.

Agree with M = modified status as above. In addition if you have a change in your Gemfile, you should run:

bundle install

to make sure that your environment matches your current gem set. This will also update your Gemfile.lock