Jehan,
I could not replicate the issue at my end while installing EGIT from MyEclipse configuration center.
Can you please try installing EGIT plugin using the update site –
> Go to MyEclipse configuration center > Software and click on Add site
> Enter some name and add this url – http://download.eclipse.org/egit/updates in the URL box and click OK
> Once you press “OK” you’ll return to the Software tab. Next, expand the update site you just added and select the plug-ins you’d like to add to MyEclipse by right-clicking on each of them and selecting “Add to profile…”. (select Eclipse EGIT and EGIT MyLyn plugins under Eclispe GIT team provider)
> After adding the plug-in to the profile you’ll see it listed as a pending change.Once all your changes are complete, select the “Apply changes…” button to download the software, follow the wizard, complete the installation, and restart MyEclipse.
After installing EGIT in MyEclipse, you can follow this EGIT guide for more information – http://wiki.eclipse.org/EGit/User_Guide
Let us know how it works for you.