This ensures that checking for newer versions of gh happens in the background of the main operation that the user requested, and that when that operation is completed, the gh process should immediately exit without being delayed by the update checker goroutine.
When gh was built from source, the version number will look something
like this since it's taken from `git describe`:
v1.4.0-34-g{SHA}
When compared as semver against `v1.4.0`, the latter version is falsely
reported as newer. This is because the output of `git describe` wasn't
meant to be interpreted as semver.
The solution is to translate the `git describe` string to faux-semver so
it can be safely compared with the version reported from the server.
Fixes this case:
A new release of gh is available: v1.4.0-41-g2f9e4cb1 → v1.4.0
https://github.com/cli/cli/releases/tag/v1.4.0
