patch: refactor file creation/removal detection
The patcher has to know if a file is being created or removed to check if the
target already exists, or to actually unlink the file when a hunk emptying it
is applied. This was done by embedding the creation/removal information in the
first (and only) hunk attached to the file.
There are two problems with this approach:
- creation/removal is really a property of the file being patched and not its
hunk.
- for regular patches, file creation cannot be deduced at parsing time: there
are case where the *stripped* file paths must be compared. Modifying hunks
after their creation is clumsy and prevent further refactorings related to
copies handling.
Instead, we delegate this job to selectfile() which has all the relevant
information, and remove the hunk createfile() and rmfile() methods.
[ original upstream message ]