Resolves cwd problem

pre_commit/prefixed_command_runner.py

@@ -17,26 +17,42 @@ class PrefixedCommandRunner(object):
 
     will run ['/tmpl/foo/foo.sh', 'bar', 'baz']
     """
-    def __init__(self, prefix_dir, popen=subprocess.Popen):
+    def __init__(self, prefix_dir, popen=subprocess.Popen, makedirs=os.makedirs):
         self.prefix_dir = prefix_dir.rstrip(os.sep) + os.sep
         self.__popen = popen
+        self.__makedirs = makedirs
 
-    def run(self, cmd, stdin=None):
+    def _create_path_if_not_exists(self):
+        if not os.path.exists(self.prefix_dir):
+            self.__makedirs(self.prefix_dir)
+
+    def run(self, cmd, retcode=0, stdin=None, **kwargs):
+        self._create_path_if_not_exists()
         replaced_cmd = _replace_cmd(cmd, prefix=self.prefix_dir)
         proc = self.__popen(
             replaced_cmd,
             stdin=subprocess.PIPE,
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
+            **kwargs
         )
         stdout, stderr = proc.communicate(stdin)
+        returncode = proc.returncode
+
+        if retcode is not None and retcode != returncode:
+            raise subprocess.CalledProcessError(
+                returncode, replaced_cmd, output=(stdout, stderr),
+            )
 
         return proc.returncode, stdout, stderr
 
-    def path(self, path_end):
-        path = os.path.join(self.prefix_dir, path_end)
+    def path(self, *parts):
+        path = os.path.join(self.prefix_dir, *parts)
         return os.path.normpath(path)
 
+    def exists(self, *parts):
+        return os.path.exists(self.path(*parts))
+
     @classmethod
     def from_command_runner(cls, command_runner, path_end):
         """Constructs a new command runner from an existing one by appending