Fix Path#relative_to for non-normalized anchor

spec/std/path_spec.cr

@@ -966,6 +966,7 @@ describe Path do
       it_relativizes("C:\\Projects", "c:\\projects\\src", "../c:\\projects\\src", "src")
       it_relativizes("C:\\Projects", "c:\\projects", "../c:\\projects", ".")
       it_relativizes("C:\\Projects\\a\\..", "c:\\projects", "../c:\\projects", ".")
+      it_relativizes("C:\\foo", "C:/bar", "../C:/bar", "..\\bar")
     end
   end
 

src/path.cr

@@ -979,19 +979,19 @@ struct Path
   # to the same roots (e.g. `\\.\C:\foo` and `C:\foo` are not equivalent, nor
   # are `\\?\UNC\server\share\foo` and `\\server\share\foo`).
   def relative_to?(base : Path) : Path?
+    # work on normalized paths otherwise we would need to backtrack on `..` parts
+    base = base.normalize
+    target = self.normalize
+
     base_anchor = base.anchor
-    target_anchor = self.anchor
+    target_anchor = target.anchor
 
     # if paths have a different anchors, there can't be a relative path between
     # them.
     if base_anchor != target_anchor
       return nil
     end
 
-    # work on normalized paths otherwise we would need to backtrack on `..` parts
-    base = base.normalize
-    target = self.normalize
-
     # check for trivial case of equal paths
     if base == target
       return new_instance(".")