The import resolution for namespace packages was wrong

With this change we can now include all parents of the script, which will make
relative imports always work.

Now the whole meta_path is scanned and not just importlib's PathFinder.

Fixes #1183.

jedi/evaluate/imports.py

@@ -21,6 +21,7 @@ from jedi._compatibility import (FileNotFoundError, ImplicitNSInfo,
                                  force_unicode, unicode)
 from jedi import debug
 from jedi import settings
+from jedi.common.utils import traverse_parents
 from jedi.parser_utils import get_cached_code_lines
 from jedi.evaluate import sys_path
 from jedi.evaluate import helpers
@@ -264,8 +265,11 @@ class Importer(object):
         )
 
     def sys_path_with_modifications(self):
-        sys_path_mod = self._evaluator.get_sys_path() \
-                       + sys_path.check_sys_path_modifications(self.module_context)
+
+        sys_path_mod = (
+            self._evaluator.get_sys_path()
+            + sys_path.check_sys_path_modifications(self.module_context)
+        )
 
         if self.import_path and self.file_path is not None \
                 and self._evaluator.environment.version_info.major == 2:
@@ -350,7 +354,8 @@ class Importer(object):
                     code, module_path, is_pkg = self._evaluator.compiled_subprocess.get_module_info(
                         string=import_parts[-1],
                         path=path,
-                        full_name=module_name
+                        full_name=module_name,
+                        is_global_search=False,
                     )
                     if module_path is not None:
                         break
@@ -358,13 +363,14 @@ class Importer(object):
                     _add_error(self.module_context, import_path[-1])
                     return NO_CONTEXTS
         else:
-            debug.dbg('search_module %s in %s', import_parts[-1], self.file_path)
+            debug.dbg('global search_module %s in %s', import_parts[-1], self.file_path)
             # Override the sys.path. It works only good that way.
             # Injecting the path directly into `find_module` did not work.
             code, module_path, is_pkg = self._evaluator.compiled_subprocess.get_module_info(
                 string=import_parts[-1],
                 full_name=module_name,
                 sys_path=sys_path,
+                is_global_search=True,
             )
             if module_path is None:
                 # The module is not a package.