node_filesystem_* Metrics deliver the Value 0

Host operating system: output of uname -a
Linux myhost 4.12.14-95.45-default #1 SMP Wed Dec 11 13:09:13 UTC 2019 (12c8180) x86_64 x86_64 x86_64 GNU/Linux

node_exporter version: output of node_exporter --version
node_exporter, version 1.0.0-rc.0 (branch: HEAD, revision: ef7c05816adcb0e8923defe34e97f6afcce0a939)
build user: root@b38a2df1a38b
build date: 20200220-12:54:05
go version: go1.13.8

Are you running node_exporter in Docker?
yes

What did you do that produced an error?
Used the Node-Exporter Version v1.0.0-rc.0 -> it works fine with the Version v0.18.1

What did you expect to see?
Values on the Metrics node_filesystem_device_error, node_filesystem_files_free, ...

What did you see instead?
The Value of the Metrics is always 0, but only on my mounted Folder.

Output in Version v1.0.0-rc.0:
node_filesystem_device_error{device="//myshare",fstype="cifs",mountpoint="/mymountpoint"} 0

Output in Version v.0.18.1:
node_filesystem_device_error{device="//myshare",fstype="cifs",mountpoint="/HOST/mymountpoint"} 0

The only difference is, that on the working Version the mountpoint ist /HOST/mountpoint instead of /mountpoint

Reproduce the issue with node_exporter 1.0.0-rc.0 and 0.18.1 in Docker using the CIFS mount, then compare the filesystem metric labels and values, especially the mountpoint path. Done means the mounted folder's node_filesystem_* metrics report the expected values and mountpoint consistently with the working version.