The new SVN patcher implementation tried to be very smart when the patch

base directory was not the same as the client base directory, filtering

out files that are not patchable. This would happen, for example, if a

patch was created in /trunk/ but the local checkout only contained

/trunk/project1/.
Unfortunately, this completely broke the use case where a patch is

created in a directory that has no overlap at all with the client (for

example, the patch was created in /trunk/project1/ but the local

checkout is /branches/release/project1/). In this case, we'd filter out

everything, attempt to apply an empty patch, and error out.
This change updates the patcher behavior to be smarter about how base

directories are dealt with. If the client is a subdirectory of the patch

base directory, we do exactly as before: filter out any files from the

patch which are not present in the client's root, and try to patch. In

all other cases, we now do two new things:

The prefix level will be computed from the patch base directory

   instead of the client's.
We just take the patch as-is (with the computed prefix level) and try

   to apply it. If there are any conflicts, it'll be up to the user to

   figure out why.

Ran unit tests, including two new tests for the subdirectory and

  no-overlap scenarios.
Checked out /trunk/ and /branches/1.14.x/ from the apache SVN

  repository. Posted one change from trunk, and then used rbt patch to

  apply it into the branch. Before this would error out with the empty

  patch, after it works correctly.