oeqa.utils: add git module

A new helper module for easier interaction with Git repositories.
Provides GitRepo class that represents one local Git repository clone.
The GitRepo class currently only has one method, run_cmd(), for running
arbitrary git commands in the repository. More specialized methods for
commonly used git operations can be added later.

(From OE-Core rev: 4eaf434f885afbda03fe67ab6e9ff291c7a9c77e)

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/git.py

@@ -0,0 +1,38 @@
+#
+# Copyright (C) 2016 Intel Corporation
+#
+# Released under the MIT license (see COPYING.MIT)
+#
+"""Git repository interactions"""
+from oeqa.utils.commands import runCmd
+
+
+class GitError(Exception):
+    """Git error handling"""
+    pass
+
+class GitRepo(object):
+    """Class representing a Git repository clone"""
+    def __init__(self, cwd):
+        self.top_dir = self._run_git_cmd_at(['rev-parse', '--show-toplevel'],
+                                            cwd)
+
+    @staticmethod
+    def _run_git_cmd_at(git_args, cwd, **kwargs):
+        """Run git command at a specified directory"""
+        git_cmd = 'git ' if isinstance(git_args, str) else ['git']
+        git_cmd += git_args
+        ret = runCmd(git_cmd, ignore_status=True, cwd=cwd, **kwargs)
+        if ret.status:
+            cmd_str = git_cmd if isinstance(git_cmd, str) \
+                                else ' '.join(git_cmd)
+            raise GitError("'{}' failed with exit code {}: {}".format(
+                cmd_str, ret.status, ret.output))
+        return ret.output.strip()
+
+    def run_cmd(self, git_args):
+        """Run Git command"""
+        return self._run_git_cmd_at(git_args, self.top_dir)
+
+
+