`arc unit`. Many of the existing test cases no longer
applied to the `splitGitDiffPaths` method; they were moved into a new
test method which also supplies values for "rename from" and "rename
to" lines.
As noted in the summary, this alters one of the expected values of an
existing test. Specifically, the following diff is a file addition of
`file` with custom prefixes, and not the addition of "dst/file":
```
diff --git src/file dst/file
new file mode 100644
index 0000000..1269488
--- /dev/null
+++ dst/file
@@ -0,0 +1 @@
+data
```