Allow for pants.ini to be missing (#47)
Allow for pants.ini to be missing (#47)

### Problem
With us introducing the command `./pants generate-pants-ini` to simplify first time setup in https://github.com/pantsbuild/pants/pull/7448, we'll be able to in a followup to that PR make an additional simplification by having `./pants generate-pants-ini` not only populate `pants.ini` but to also create it.

So, when a user first curls the bootstrap script, we will no longer have them `touch pants.ini`.

However, without `pants.ini`, our parsing function will result in a sed error that the file cannot be found.

### Solution
Only try to parse `pants.ini` if it exists.
pantsbuild/setup,jsirois/setup,jsirois/setup,jsirois/setup,pantsbuild/setup,pantsbuild/setup