projects: don't explode trying to update UpdateDocsTaskStep state

If we don't have it because setup_env hasn't been called yet.

Traceback (most recent call last):
  File "/readthedocs/projects/tasks.py", line 313, in run
    self.version = self.get_version(self.project, version_pk)
  File "/readthedocs/projects/tasks.py", line 84, in get_version
    version_data = api_v2.version(version_pk).get()
  File "/lib/python3.5/site-packages/slumber/__init__.py", line 155, in get
    resp = self._request("GET", params=kwargs)
  File "/lib/python3.5/site-packages/slumber/__init__.py", line 101, in _request
    raise exception_class("Client Error %s: %s" % (resp.status_code, url), response=resp, content=resp.content)
slumber.exceptions.HttpNotFoundError: Client Error 404: http://localhost:8002/api/v2/version/868/

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/docsitalia/management/commands/rebuild_projects.py", line 33, in handle
    task.run(version.project.pk, version_pk=version.pk, build_pk=build.pk)
  File "/readthedocs/projects/tasks.py", line 332, in run
    build_id=build_pk,
AttributeError: 'UpdateDocsTaskStep' object has no attribute 'setup_env'

While at it do the same for build_env that may be not set if run_build
fail early.

Author: xrmx

readthedocs/projects/tasks.py

@@ -286,6 +286,7 @@ def __init__(self, build_env=None, python_env=None, config=None,
         if config is not None:
             self.config = config
         self.task = task
+        self.setup_env = None
 
     def _log(self, msg):
         log.info(LOG_TEMPLATE
@@ -355,12 +356,13 @@ def run(self, pk, version_pk=None, build_pk=None, record=True,
                     },
                 },
             )
-            self.setup_env.failure = BuildEnvironmentError(
-                BuildEnvironmentError.GENERIC_WITH_BUILD_ID.format(
-                    build_id=build_pk,
+            if self.setup_env is not None:
+                self.setup_env.failure = BuildEnvironmentError(
+                    BuildEnvironmentError.GENERIC_WITH_BUILD_ID.format(
+                        build_id=build_pk,
+                    )
                 )
-            )
-            self.setup_env.update_build(BUILD_STATE_FINISHED)
+                self.setup_env.update_build(BUILD_STATE_FINISHED)
             return False
         else:
             # No exceptions in the setup step, catch unhandled errors in the
@@ -379,12 +381,13 @@ def run(self, pk, version_pk=None, build_pk=None, record=True,
                         },
                     },
                 )
-                self.build_env.failure = BuildEnvironmentError(
-                    BuildEnvironmentError.GENERIC_WITH_BUILD_ID.format(
-                        build_id=build_pk,
+                if self.build_env is not None:
+                    self.build_env.failure = BuildEnvironmentError(
+                        BuildEnvironmentError.GENERIC_WITH_BUILD_ID.format(
+                            build_id=build_pk,
+                        )
                     )
-                )
-                self.build_env.update_build(BUILD_STATE_FINISHED)
+                    self.build_env.update_build(BUILD_STATE_FINISHED)
                 return False
 
         return True