dvc: don't use $SHELL on windows

Related to #1238

Signed-off-by: Ruslan Kuprieiev <[email protected]>

dvc/remote/hdfs.py

@@ -34,10 +34,11 @@ class RemoteHDFS(RemoteBase):
         # See https://github.com/iterative/dvc/issues/1197.
         close_fds = (os.name != 'nt')
 
+        executable = os.getenv('SHELL') if os.name != 'nt' else None
         p = Popen(cmd,
                   shell=True,
                   close_fds=close_fds,
-                  executable=os.getenv('SHELL'),
+                  executable=executable,
                   env=fix_env(os.environ),
                   stdin=PIPE,
                   stdout=PIPE,

dvc/stage.py

@@ -440,11 +440,12 @@ class Stage(object):
 
             if not dry:
                 self._check_missing_deps()
+                executable = os.getenv('SHELL') if os.name != 'nt' else None
                 p = subprocess.Popen(self.cmd,
                                      cwd=self.cwd,
                                      shell=True,
                                      env=fix_env(os.environ),
-                                     executable=os.getenv('SHELL'))
+                                     executable=executable)
                 p.communicate()
                 if p.returncode != 0:
                     raise StageCmdFailedError(self)