why there is a file named run-vmblock\x2dfuse.mount about pkg-open-vm-tools

[bzed]

Please open a bug against dpkg then.

That name is just a standard systemd mount unit. Details regarding the escaping are defined in the systemd.unit manpage:

Some unit names reflect paths existing in the file system namespace. Example: a device unit dev-sda.device refers to a device with the device node /dev/sda in the file system namespace. If this applies, a special way to escape the path name is used, so that the result is usable as part of a filename. Basically, given a path, "/" is replaced by "-", and all other characters which are not ASCII alphanumerics are replaced by C-style "\x2d" escapes (except that "_" is never replaced and "." is only replaced when it would be the first character in the escaped path). The root directory "/" is encoded as single dash, while otherwise the initial and ending "/" are removed from all paths during transformation. This escaping is reversible. Properly escaped paths can be generated using the systemd-escape(1) command.

[bzed]

Actually the bug is not in dpkg, but in debhelper.

[bzed]

Bug#843163: dpkg: -V fails on files with \ in the name
http://bugs.debian.org/843163