patman: RunPipe() should not pipe stdout/stderr unless asked

RunPipe() currently pipes the output of stdout and stderr to a pty, but
this is not the intended behaviour. Fix it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/command.py b/tools/patman/command.py
index 449d3d0..7212fdf 100644
--- a/tools/patman/command.py
+++ b/tools/patman/command.py
@@ -48,6 +48,8 @@
     last_pipe = None
     pipeline = list(pipe_list)
     user_pipestr =  '|'.join([' '.join(pipe) for pipe in pipe_list])
+    kwargs['stdout'] = None
+    kwargs['stderr'] = None
     while pipeline:
         cmd = pipeline.pop(0)
         if last_pipe is not None:
diff --git a/tools/patman/gitutil.py b/tools/patman/gitutil.py
index 80edc7c..b68df5d 100644
--- a/tools/patman/gitutil.py
+++ b/tools/patman/gitutil.py
@@ -152,7 +152,8 @@
     if force:
         pipe.append('-f')
     pipe.append(commit_hash)
-    result = command.RunPipe([pipe], capture=True, raise_on_error=False)
+    result = command.RunPipe([pipe], capture=True, raise_on_error=False,
+                             capture_stderr=True)
     if result.return_code != 0:
         raise OSError, 'git checkout (%s): %s' % (pipe, result.stderr)
 
@@ -163,7 +164,8 @@
         commit_hash: Commit hash to check out
     """
     pipe = ['git', 'clone', git_dir, '.']
-    result = command.RunPipe([pipe], capture=True, cwd=output_dir)
+    result = command.RunPipe([pipe], capture=True, cwd=output_dir,
+                             capture_stderr=True)
     if result.return_code != 0:
         raise OSError, 'git clone: %s' % result.stderr
 
@@ -179,7 +181,7 @@
     if work_tree:
         pipe.extend(['--work-tree', work_tree])
     pipe.append('fetch')
-    result = command.RunPipe([pipe], capture=True)
+    result = command.RunPipe([pipe], capture=True, capture_stderr=True)
     if result.return_code != 0:
         raise OSError, 'git fetch: %s' % result.stderr