Tests failed: m_assume_storage_prezeroed (when /tmp is not a tmpfs)

[xry111]

The precise number of block used seems depending on the underlying file system for /tmp (where the test file is created). The number 224 seems only valid for tmpfs. On other FS I've got numbers like 232 or 496.

Should we skip the test if /tmp is not a mountpoint for tmpfs, or check if the actual number is smaller than a threshold instead of equal with a precise number?