Describe the bug
When running vcpkg install it works (exit code 0). When running it again, it says:

Failed to take the filesystem lock on /home/USER/vcpkg/.vcpkg-root

Environment

• OS: Ubuntu 18.04
• Corporate Proxy

To Reproduce
Have an install only install local overlay ports and a corporate proxy blocking access to the outside internet. However vcpkg shouldn't need internet access for any of these if the resources are local.

Steps to reproduce the behavior:

1. ./vcpkg install
2. ./vcpkg install

Expected behavior
Lock is given up after install finishes.

Failure logs
None

Additional context

1. Running pkill curl allows executing vcpkg again, but only once. lsof curl | rg -i vcpkg shows that curl seems to be hanging here and keeping the file system locked.
2. I did use -disableMetrics when bootstrapping vcpkg. So it shouldn't be any telemetrics. But maybe this flag is ignored.
3. vcpkg was built from latest tag:

$ vcpkg version
Vcpkg package management program version 2020.06.15-unknownhash