TAP runner executes tests twice when file watching is enabled

[lfurzewaddock]

I'm using Tape v4.9.1 to test a simple CommonJS module without any other dependencies.

Upon saving a file in the 'src' directory or the 'test' directory, tests execute twice. However, hitting the return key in the terminal runs the tests once as expected.

I've attempted to debug testem in node_modules and can see 'start' in class 'TapProcessTestRunner', file '/lib/runners/tap_process_test_runner.js' is being called twice.

issue #1143 appears to be similar.

Environment

MS Windows 10 Pro WSL (Windows Subsystem for Linux) environment.
MS Windows 10 Version: 1803
MS Windows 10 OS build: 17134.228

WSL Details:
OS: Ubuntu 16.04.4 LTS (Xenial Xerus)
CPU: x64 Intel(R) Xeon(R) CPU E5-2640 0 @ 2.50GHz
Shell: 4.3.48 - /bin/bash
Node: 8.11.2 - ~/.nvm/versions/node/v8.11.2/bin/node