Hi ,
We were also experiencing this issue and the suggested work around above, recompiling GitDependencies.exe with a HTTPS url worked for us, however our IT department looked at it and found some insights that might be helpful.
Apparently the Gateway Anti-Virus is detecting it as a worm, in our case it’s detected as Conficker.gen. Our IT department has added an IP address for cdn.unrealengine.com to the bypass list, but obviously this might change and is probably not the best longterm solution.
SonicWALL Alert
Hope this info helps.