fix scm history going out of sync after commit

[erezmus]

What it does

• Fixes Git extension widgets "Git" and "Git History" not synchronized #2922 issue where new git commits don't appear in the history view
• Also fixes duplicate commits appearing in the history view

How to test

• open a git repository
• change a file and commit it
• switch to the history view
• the commit should appear at the top

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[vince-fugnitto]

@erezmus thank you for the contribution, can you confirm if you are also seeing this bug which I experienced with the pull-request:

• start the application with a workspace under git version control (I was on master)
• make some changes
• commit the changes
• open the history-view and the new commit is present
• in the terminal perform a hard reset (ex: git reset --hard origin/master)
• the history-view will fail to show any history

[erezmus]

@vince-fugnitto correct, i can reproduce it. will fix

[erezmus]

Pushed a new fix and also added caching of avatars.

[vince-fugnitto]

The updated changes look good to me 👍
Do you mind force pushing to restart the eca check (it seems to be hanging and is required).

[msujew]

Your code never calls set on this cache. Is it an oversight, or am I missing something?

Outstanding comments #12592 (comment)

[msujew]

@erezmus Ping! Please address #12592 (comment).

[CareyJWilliams]

@erezmus isn't likely to be available to address this until September. I put up another PR based off of this one that I believe makes the desired change: #12837

Though if we're happy to wait for him to return that is fine too.