Whilst trying to use the upgrade installer from version 3.9.14998 to the latest available version: 3.9.15054 the installer hangs at 44% just after the easysocial file.
This seems to be a constant problem upgrading from one version to another using the installer, and hasn't worked correctly for several months.
I have to ask whether you actually test upgrades before they are released, because on my experience alone it doesn't appear so!