test-convert-darcs.t: fix elementtree test
On OSX, the test succeeds because darcs aborts when trying to convert
the dummy repository, and the test only grep for the output. On Windows,
the darcs call succeeds for some reason but darcs fails to emit any output,
which is not a valid XML output, which causes a traceback including the
ElementTree string matched by the check, and makes a false positive.
Check with a real repository instead. The darcs upgrade test is moved
at the end so we can use our handmade darcs repository for the test.
Hello, Foobar
['Hello, Fo, =;o', 'Hello, Bar']