Commit 968d1c3 (Portability) introduced a bug with some very POSIX
compliant shells (eg dash), which don't do brace expansion. So add a
test for that.
The test runs by adding a new protocol in Uri, sh+cp://path/. This
protocol is not intended to be used normally, but is only for testing
the push and pull code.
Signed-off-by: Russell Steicke <russells@adelie.cx>
