mrtrix3: use looseversion to avoid undefined version

Author: ihnorton

nipype/interfaces/mrtrix3/base.py

@@ -4,7 +4,7 @@
 from __future__ import (print_function, division, unicode_literals,
                         absolute_import)
 
-from ... import logging
+from ... import logging, LooseVersion
 from ...utils.filemanip import which
 from ..base import (CommandLineInputSpec, CommandLine, traits, File, isdefined, PackageInfo)
 iflogger = logging.getLogger('nipype.interface')
@@ -30,6 +30,18 @@ def parse_version(raw_info):
 
         return '.'.join(v_string.split('.')[:3])
 
+    @classmethod
+    def looseversion(cls):
+        """ Return a comparable version object
+
+        If no version found, use LooseVersion('0.0.0')
+        """
+        ver = cls.version()
+        if ver is None:
+            return LooseVersion('0.0.0')
+
+        return cls.version())
+
 
 class MRTrix3BaseInputSpec(CommandLineInputSpec):
     nthreads = traits.Int(

nipype/interfaces/mrtrix3/reconst.py

@@ -75,7 +75,7 @@ class FitTensor(MRTrix3Base):
     """
 
     _cmd = 'dwi2tensor'
-    if Info.version() < LooseVersion("0.3.14"):
+    if Info.looseversion() < LooseVersion("0.3.14"):
         input_spec = FitTensorInputSpec0_3_13
     else:
         input_spec = FitTensorInputSpec