fix(ignore, fs): allow loading ignore patterns behind symlink (fixes #10785) (#10786)

The recent change to disallow following symlinks by default conflicts
with the expected behavior of .stignore. This adds a new flag which may
be passed to OpenFile to skip default symlink-forbidding open flag.

---------

Signed-off-by: Jakob Borg <jakob@kastelo.net>

lib/ignore/ignore.go

@@ -357,8 +357,8 @@ func hashPatterns(patterns []Pattern) string {
 	return hex.EncodeToString(h.Sum(nil))
 }
 
-func loadIgnoreFile(fs fs.Filesystem, file string) (fs.File, fs.FileInfo, error) {
-	fd, err := fs.Open(file)
+func loadIgnoreFile(ffs fs.Filesystem, file string) (fs.File, fs.FileInfo, error) {
+	fd, err := ffs.OpenFile(file, fs.OptReadOnly|fs.OptFollow, 0o666)
 	if err != nil {
 		return fd, nil, err
 	}