dirstate-v2: adds a flag to mark a file as modified Right now, a files with a file system state that requires a lookup (same size, different mtime) will requires a lookup. If the result of that lookup is a modified files, it will remains ambiguous, requiring a lookup on the next status run too. To fix this, we introduce a dedicated flag in the new format. Such flag will allow to record such file as "known modified" avoiding an extra lookup later. As None of the associate code currently exist in the status code, we do the minimal implementation: if we read a dirstate entry with this flag set, we make it as "ambiguous" so that the next status code has to look it up. The same as it would have to without this flag existing anyway. Differential Revision: https://phab.mercurial-scm.org/D11681