I'm trying to get through my first GHC patch submission, using git and Phabricator, following directions at
https://ghc.haskell.org/trac/ghc/wiki/Phabricator. "git status" shows two unstaged changes: "deleted: test spaces" and "modified: ../libraries/bytestring (modified content)" (in a submodule). I don't know where either change came from. When I use "arc diff" to submit my intended change to the compiler, I get asked about these to uncommitted changes. I say to ignore the submodule change and do not amend my commit with the "test spaces" deletion, I get "Usage Exception: You can not continue with uncommitted changes. Commit or discard them before proceeding." I don't know how to discard (nor whether safe), and I don't think I want to commit.