merge: let bid merge work on the file->action dict By moving the conversion from the file->action dict after the bid merge code, bid merge can be simplified a little. A few tests are affected by this change. Where we used to iterate over the actions first in order of the action type ('g', 'r', etc.) [1], we now iterate in order of filename. This difference affects the order of debug log statements. [1] And then in the non-deterministic order of files in the manifest dictionary (the order returned from manifest.diff()).