Fix error with different drive letters

Revert two methods in RefinePathname to their previous implementations. Plan to find a correct handling approach for different drive letters in the future and revert this commit.

lib/ocran/refine_pathname.rb

@@ -43,15 +43,34 @@ def eql?(other)
       alias == eql?
       alias === eql?
 
+      # Compute the relative path from the 'src' path (directory) to 'tgt'
+      # (directory or file). Return the absolute path to 'tgt' if it can't
+      # be reached from 'src'.
+      def relative_path_from(other)
+        a = to_s.split(Pathname::SEPARATOR_PAT)
+        b = other.to_s.split(Pathname::SEPARATOR_PAT)
+        while a.first && b.first && pathequal(a.first, b.first)
+          a.shift
+          b.shift
+        end
+        return other if b.first && Pathname.new(b.first).absolute?
+        b.size.times { a.unshift ".." }
+        Pathname.new(File.join(*a))
+      end
+
       # Checks if the current path is a subpath of the specified base_directory.
       # Both paths must be either absolute paths or relative paths; otherwise, this
       # method returns false.
       def subpath?(base_directory)
-        relative_path = relative_path_from(base_directory)
-        s = relative_path.to_s
-        s != '.' && s !~ /\A\.\.#{Pathname::SEPARATOR_PAT}/
-      rescue ArgumentError
-        false
+        base_directory = Pathname.new(base_directory) unless base_directory.is_a?(Pathname)
+        src_normalized = to_posix
+        tgt_normalized = base_directory.to_posix
+        src_normalized =~ /^#{Regexp.escape tgt_normalized}#{Pathname::SEPARATOR_PAT}/i
+      #   relative_path = relative_path_from(base_directory)
+      #   s = relative_path.to_s
+      #   s != '.' && s !~ /\A\.\.#{Pathname::SEPARATOR_PAT}/
+      # rescue ArgumentError
+      #   false
       end
 
       # Appends the given suffix to the filename, preserving the file extension.