Recover a Lost Commit Message

Today, I was writing a long, careful git commit message. No git commit -m "fixes" for me—this was a real novel. It had bulleted lists, and links to tickets and related pull requests. I finished up my message, typed <esc>-:wq-<enter> to exit vim and…

***ERROR***: Invalid commit message.

On a task branch (i.e. branch with a JIRA ticket ID in it's name, like
SF-XXX where SF-XXX is the id of your Jira ticket), all commit messages must
start with the JIRA ticket's ID, in all caps. Merge commits are also allowed.

  SF-XXX Made some changes

[... more advice, snipped ...]


A git post-commit hook cancelled my commit! For a moment, panic. Would I need to rewrite that whole thing? Luckily, some googling turned up the following:

In order to commit, your editor MUST write the commit message to the file .git/COMMIT_EDITMSG and exit with a 0 status code.

Maybe the message is still there, in .git/COMMIT_EDITMSG? It was! My day is saved! I was able to grab the full text and copy it into a new commit message.