init: fixed issue with self.path section missing in west.yml

Fixes: #218

Using empty string instead of None as None results in error when
instantiating Manifest project as special project.

Signed-off-by: Torsten Rasmussen <torsten.rasmussen@nordicsemi.no>

src/west/commands/project.py

@@ -65,9 +65,11 @@ class PostInit(WestCommand):
             rel_manifest = os.path.relpath(args.local, util.west_topdir())
             _update_key(config, 'manifest', 'path', rel_manifest)
         else:
-            if project.path is None:
+            if project.path == '':
                 url_path = urlparse(args.manifest_url).path
                 project.path = posixpath.basename(url_path)
+                project.abspath = os.path.realpath(
+                    os.path.join(util.west_topdir(), project.path))
                 project.name = project.path
 
             _inf(project, 'Creating repository for {name_and_path}')

src/west/manifest.py

@@ -207,7 +207,7 @@ class Manifest:
 
         self_tag = manifest.get('self')
         if path is None:
-            path = self_tag.get('path') if self_tag else None
+            path = self_tag.get('path') if self_tag else ''
         west_commands = self_tag.get('west-commands') if self_tag else None
 
         project = SpecialProject(path, path=path, west_commands=west_commands)