tests: make directory to prevent test process from going out of $TESTTMP
Before this patch, test process for test-bookmarks.t goes out of
$TESTTMP at "cd .." before creation of "orderrepo" repository.
To prevent test process from going out of $TESTTMP, this patch makes
directory "repo" sub-directory and executes almost all test scenarios
in test-bookmarks.t under it.
This is preparation for new test added in subsequent patch.
wrap 0: [0, 'orig']
wrap 1: [1, 0, 'orig']
wrap 2: [2, 1, 0, 'orig']
wrap 3: [3, 2, 1, 0, 'orig']
wrap 4: [4, 3, 2, 1, 0, 'orig']
wrap 0: [0, 4, 3, 2, 1, 0, 'orig']
unwrap 3: 3: [0, 4, 2, 1, 0, 'orig']
unwrap -: 0: [4, 2, 1, 0, 'orig']
unwrap 0: 0: [4, 2, 1, 'orig']
unwrap 4: 4: [2, 1, 'orig']
unwrap 0: -: ValueError
unwrap 2: 2: [1, 'orig']
unwrap 1: 1: ['orig']
unwrap -: -: IndexError