It was possible for a interrupted sync or merge in direct mode to
leave the work tree out of sync with the last recorded commit.
This would result in the next commit seeing files missing from the work
tree, and committing their removal.
Now, a direct mode merge happens not only in a throwaway work tree, but using
a temporary index file, and without any commits or index changes
being made until the real work tree has been updated. If the merge is
interrupted, the work tree may have some updated files, but worst case a
commit will redundantly commit changes that come from the merge.
This commit was sponsored by Tony Cantor.
This is a new feature, it was not handled before, since it's a bit of an
edge case. However, it can be handled exactly the same as a file/dir
conflict, just leave the non-annexed item alone.
While implementing this, the core resolveMerge' function got a lot simpler
and clearer. Note especially that where before there was an asymetric call to
stagefromdirectmergedir, now graftin is called symmetrically in both cases.
And, in order to add that `graftin us`, the current branch needed to be
known (if there is no current branch, there cannot be a merge conflict).
This led to some cleanups of how autoMergeFrom behaved when there is no
current branch.
This commit was sponsored by Philippe Gauthier.
