Support for sparse files in LxFS (flow type checker fails)

• A brief description
  I downloaded 0.40.0 version from its repository and tried to run it.

• Expected results
  Flow checking my files.

• Actual results (with terminal output if applicable)

Launching Flow server for /mnt/c/projects/jstraining
Spawned flow server (pid=34)
Logs will go to /tmp/flow/zSmntzSczSprojectszSjstraining.log
Error: Failed to start server. exited prematurely with code 2.
Could not start Flow server!

• Your Windows build number
  15042
• Steps / All commands required to reproduce the error from a brand new installation

1. download the flow binary from github repo
2. chmod 755 flow
3. touch .flowconfig
4. ./flow

• Strace of the failing command
  strace flow.zip
• Required packages and commands to install
  Flow 0.40.0

Edit: attached strace files. Also found flow works fine on another machine which has way more disk space available. Considering reinstalling subsystem now.

Start by reproducing the failure with Flow 0.40.0, an empty .flowconfig, and ./flow on Windows build 15042. Read the attached strace and compare the behavior on the machine where Flow works. Done means the Flow server starts successfully when the binary and project are on LxFS.