Previously we would have tried to do the rebase, resulting in a long and
somewhat cryptic error message from git; now we check ourselves and show a less
intimidating message.
This fixes the problem that patching would stop at the first file that has a
conflict. We always want to patch all files.
Also, it's faster for large patches, and the code is a little bit simpler too.
The patch contains changes to two files; the first one conflicts, the second
doesn't. Note how it only applies changes to the first file at this point in the
branch; we'll fix this in the next commit.
This test would fail on master for multiple reasons.
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.
