runcli.py: fix linting errors

In order to expose integration.py as part of teh public testing api,
we need to move it into the buildstream module. First we should fix
various linting errors.

buildstream/plugintestutils/runcli.py

@@ -5,7 +5,6 @@ import shutil
 import tempfile
 import itertools
 import traceback
-import subprocess
 from contextlib import contextmanager, ExitStack
 from ruamel import yaml
 import pytest
@@ -327,7 +326,7 @@ class Cli():
 
         return result
 
-    def invoke(self, cli, args=None, color=False, binary_capture=False, **extra):
+    def invoke(self, cli_object, args=None, color=False, binary_capture=False, **extra):
         exc_info = None
         exception = None
         exit_code = 0
@@ -342,7 +341,7 @@ class Cli():
             capture.start_capturing()
 
             try:
-                cli.main(args=args or (), prog_name=cli.name, **extra)
+                cli_object.main(args=args or (), prog_name=cli_object.name, **extra)
             except SystemExit as e:
                 if e.code != 0:
                     exception = e
@@ -355,7 +354,7 @@ class Cli():
                     sys.stdout.write(str(exit_code))
                     sys.stdout.write('\n')
                     exit_code = 1
-            except Exception as e:
+            except Exception as e:  # pylint: disable=broad-except
                 exception = e
                 exit_code = -1
                 exc_info = sys.exc_info()