If you ran this test enough times it would eventually fail; this happened
whenever the resulting squashed commit had a sha that happened to start with
"02". We test that "commit 02" does not appear in the diff window, but in that
case it did, at the very top of the window.
A better fix might be to change the commit message that we use in CreateNCommits
to something other than "commit XY", but that would require touching tons of
tests, so this is the easier fix.
It's not so much the total number of commits that matters here, it's just
whether we are on the first one. (This includes the other condition.)
This allows us to get rid of the condition in rebase.go.
We already have this very convenient behavior of jumping to the next stageable
line after staging something. However, while this worked well for staging
single lines or hunks, it didn't work correctly when staging a range of lines;
in this case we want to start searching from the first line of the range.
While we try to keep the view's cursor position in sync with the context state's
selectedLineIdx (at least when pressing up or down), there are enough situations
where the two run out of sync; for example when initially opening the view, or
after staging a hunk, or when scrolling the view using the wheel. While it would
be possible to fix these situations to keep them always in sync, it doesn't seem
worth it, because the view's cursor position isn't really used for anything
else. So we rather special-case the SelectedLine/SelectedLineIdx functions of
ViewDriver to query the context state's selectedLineIdx directly if it is a
patch explorer context.
