Merge branch 'jk/difftool-dir-diff-edit-fix'

"git difftool --dir-diff" made symlinks to working tree files when preparing a temporary directory structure, so that accidental edits of these files in the difftool are reflected back to the working tree, but the logic to decide when to do so was not quite right. * jk/difftool-dir-diff-edit-fix: difftool --dir-diff: symlink all files matching the working tree difftool: avoid double slashes in symlink targets git-difftool(1): fix formatting of --symlink description