Bug#911862: fontconfig: Obscure message: "Unable to revert mtime: /usr/local/share/fonts"

[boffi]

Package: fontconfig
Version: 2.13.1-1
Severity: normal

Dear Maintainer,

every time I use a program that accesses the fontconfig system
I'm told on stderr

    Unable to revert mtime: /usr/local/share/fonts

While it's not a showstopper problem it is something that
could be addressed...

I do have a /usr/local/share/fonts directory, initially it was empty
but later I tried to  touch an empty file: I had the warning before
I created the empty file and I have the warning now.

Permissions?

$ ls -ld /usr/local/share/fonts/
drwxrwsr-x 2 root staff 4096 Oct 25 17:33 /usr/local/share/fonts//
$ ls -l /usr/local/share/fonts/
total 0
-rw-r--r-- 1 boffi staff 0 Oct 25 17:28 asdef
$ groups
boffi ... staff ...
$

Thanks a lot  ፨ gb 
-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.18.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE=C.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages fontconfig depends on:
ii  fontconfig-config  2.13.1-1
ii  libc6              2.27-6
ii  libfontconfig1     2.13.1-1
ii  libfreetype6       2.8.1-2

fontconfig recommends no packages.

fontconfig suggests no packages.

-- no debconf information