relocate_text: fix return value (#48568)

lib/spack/spack/relocate_text.py

@@ -209,7 +209,7 @@ def _apply_to_file(self, f):
         # but it's nasty to deal with matches across boundaries, so let's stick to
         # something simple.
 
-        modified = True
+        modified = False
 
         for match in self.regex.finditer(f.read()):
             # The matching prefix (old) and its replacement (new)