Fix wizard mkdir (#824)

* Fix CLI wizard mkdir_p with empty path

Fixes https://github.com/esphome/issues/issues/796

* Cleanup

* Lint

esphome/helpers.py

@@ -80,6 +80,9 @@ def run_system_command(*args):
 
 
 def mkdir_p(path):
+    if not path:
+        # Empty path - means create current dir
+        return
     try:
         os.makedirs(path)
     except OSError as err:

esphome/storage_json.py

@@ -7,7 +7,7 @@ import os
 
 from esphome import const
 from esphome.core import CORE
-from esphome.helpers import mkdir_p, write_file_if_changed
+from esphome.helpers import write_file_if_changed
 
 # pylint: disable=unused-import, wrong-import-order
 from esphome.core import CoreType  # noqa
@@ -88,7 +88,6 @@ class StorageJSON(object):
         return json.dumps(self.as_dict(), indent=2) + u'\n'
 
     def save(self, path):
-        mkdir_p(os.path.dirname(path))
         write_file_if_changed(path, self.to_json())
 
     @staticmethod

esphome/writer.py

@@ -286,8 +286,6 @@ or use the custom_components folder.
 
 
 def copy_src_tree():
-    import shutil
-
     source_files = {}
     for _, component, _ in iter_components(CORE.config):
         source_files.update(component.source_files)
@@ -326,8 +324,7 @@ def copy_src_tree():
     # Now copy new files
     for target, src_path in source_files_copy.items():
         dst_path = CORE.relative_src_path(*target.split('/'))
-        mkdir_p(os.path.dirname(dst_path))
-        shutil.copy(src_path, dst_path)
+        copy_file_if_changed(src_path, dst_path)
 
     # Finally copy defines
     write_file_if_changed(CORE.relative_src_path('esphome', 'core', 'defines.h'),