Await file creation promise when pushing a newly created file

[benhatsor]

Creating a file and immediately changing it and trying to push results in an error.

Creating a file with a specific name and specific directory contents results in an error, like so:

Directory contents:
file.js
file-1.js

New file name:
file.js

Corrects to:
file-1.js

Attempting to push two files with the same name results in an error.