manifest: extract method for parsing manifest By extracting a method that generates (path, node, flags) tuples, we can reuse the code for parsing a manifest without doing it via a _lazymanifest like treemanifest currently does. It also prepares for parsing the new manifest format. Note that this makes parsing into treemanifest slower, since the parsing is now always done in pure Python. Since treemanifests will be expected (or even forced) to be used only with the new manifest format, parsing via _lazymanifest was not an option anyway.

dirstate._walkexplicit: don't bother normalizing '.' The overwhelmingly common case is running commands like 'hg diff' with no arguments. Therefore the only file that'll be listed is the root directory. Normalizing that's just a waste of time. This means that for a plain 'hg diff' we'll never need to construct the foldmap, saving us a significant chunk of time. On case-insensitive HFS+ on OS X, for a large repository with over 200,000 files, this brings down 'hg diff' from 2.97 seconds to 2.36.

dirstate._walkexplicit: drop normpath calls The paths the matcher returns are normalized already.

dirstate._walkexplicit: indicate root as '.', not '' '.' is the canonical way to represent the root, and it's apparently the only transformation that normpath makes.

phases: add killswitch for native implementation

phases: move pure phase computation in a function