put output of atomic [un,]mount to logger, not colin's stdout

Fixes #179

Signed-off-by: Tomas Tomecek <[email protected]>

colin/core/target.py

@@ -407,10 +407,11 @@ def _run_and_log(cmd, ostree_repo_path, error_msg, wd=None):
         if wd:
             kwargs["cwd"] = wd
         try:
-            subprocess.check_call(cmd, **kwargs)
+            out = subprocess.check_output(cmd, **kwargs)
         except subprocess.CalledProcessError:
             logger.error(error_msg)
             raise
+        logger.debug("%s", out)
 
     @property
     def config_metadata(self):