Interactive Rebase sometimes hangs

**Describe the bug**
I'm not sure why it happens but sometimes an interactive rebase will simply hang. Most recent example is when squashing 8 commits in a row, with the parent commit being a merge commit.

**Expected behavior**
If there is a prompt that requires user input, we should switch to that subprocess.

**Desktop (please complete the following information):**
- OS: OXS
- Lazygit Version v0.8 (but it probably still happens on later versions)

**Additional context**
Really want to make this interactive rebase thing robust so that people feel safe using it.