I didn’t know until recently that GitDependencies did caching. Unfortunately, the one that comes with even 4.8 is missing env variable support to allow it to work how I would like, so I added it.
With this enhancement, you can add UE4_GITDEPS_CACHESIZE and UE4_GITDEPS_CACHEDAYS to your environment variables and they’ll be respected globally, along with UE4_GITDEPS (which is the original exposed env variable for the global cache path.)
I discuss the changes in the article I posted today: Easier caching with environment variables and GitDependencies.exe.