A long long time ago (like late 90s) Microsoft bought, whole hog, the source to Perforce and created "Source Depot". Something they never released to the public. I believe this is what the Windows team used. While I do think they might have been able to sell Source Depot as a product, I'm not sure they could have open sourced it.
The fact that GVFS can even be open sourced is also probably another reason for making the move.
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A long long time ago (like late 90s) Microsoft bought, whole hog, the source to Perforce and created "Source Depot". Something they never released to the public. I believe this is what the Windows team used. While I do think they might have been able to sell Source Depot as a product, I'm not sure they could have open sourced it.
The fact that GVFS can even be open sourced is also probably another reason for making the move.