transplant: handle non-empty patches doing nothing (issue2806) If patch.patch() reports patched files when applying a changeset and the following commit says nothing changed, transplant used to abort with a RuntimeError, assuming something went wrong with patching. The mismatch is patch.patch() reports patched files, not changed ones. It could be modified to report changed files but it means duplicating work from status, may be expensive in the case of binary files, and is probably not that useful at API level. For instance, if two patches are applied on the working directory, the outcome may be nothing changed while each call would have returned modified files. The caller would have to call status() itself again. This patch fixes the issue by trusting patching code: if the patch succeeded and commit reports nothing changed, then nothing changed, patch() did not "dropped changes on the floor".