Update nipype/interfaces/base/traits_extension.py [skip ci]

Co-Authored-By: Chris Markiewicz <effigies@gmail.com>

Author: oesteban

nipype/interfaces/base/traits_extension.py

@@ -135,7 +135,7 @@ def validate(self, objekt, name, value, return_pathlike=False):
             self.error(objekt, name, str(value))
 
         if self.exists:
-            if self.exists and not value.exists():
+            if not value.exists():
                 self.error(objekt, name, str(value))
 
             if self._is_file and not value.is_file():