Merge pull request #2548 from iterative/py27

fix py27 compat

dvc/logger.py

@@ -2,7 +2,7 @@
 
 from __future__ import unicode_literals
 
-from dvc.utils.compat import str, StringIO
+from dvc.utils.compat import str, StringIO, RecursionError
 from dvc.progress import Tqdm
 
 import logging

dvc/utils/compat.py

@@ -18,6 +18,11 @@ is_py3 = _ver[0] == 3
 # simplified version of ipython_genutils/encoding.py
 DEFAULT_ENCODING = sys.getdefaultencoding()
 
+if _ver[:2] < (3, 5):
+    RecursionError = RuntimeError
+else:
+    RecursionError = RecursionError
+
 
 def no_code(x, encoding=None):
     return x