Merge remote-tracking branch 'origin/pr/693'

* origin/pr/693:
  lvm: suppress logs on stdout when expecting json output

Author: marmarek

qubes/storage/lvm.py

@@ -234,6 +234,7 @@ def usage_details(self):
 _init_cache_cmd = [
     _lvm,
     "lvs",
+    "--quiet",
     "--noheadings",
     "-o",
     "vg_name,pool_lv,name,lv_size,data_percent,lv_attr,origin,lv_metadata_size,"