When a binary source has been copied or renamed into a non-binary
file, we don't check whether the copy source was binary. There is a
code comment explaining that a git mode will be forced anyway in order
to capture the copy record (i.e. losedatafn() will be called). This is
true, but forcing git mode is not the only effect binary files have:
when git mode was already requested, we use the binary-ness to tell us
whether to use a regular unified diff or a git binary diff. The user
sees this as a "Binary file $file has changed" instead of the binary
Many tests didn't change back from subdirectories at the end of the tests ...
and they don't have to. The missing 'cd ..' could always be added when another
test case is added to the test file.
This change do that tests (99.5%) consistently end up in $TESTDIR where they
started, thus making it simpler to extend them or move them around.
