fix error in pathogen#runtime_append_all_bundles

```
Error detected while processing function pathogen#runtime_append_all_bundles:
line    6:
E118: Too many arguments for function: copy
E116: Invalid arguments for function map(copy(a:000, 'v:val . "/{}"'))
E116: Invalid arguments for function call('pathogen#incubate', map(copy(a:000, 'v:val . "/{}"'))
E15: Invalid expression: call('pathogen#incubate', map(copy(a:000, 'v:val . "/{}"'))

```

Another typo :)