Control: found -1 2.13.1-2 It's still reproducible for me:
$ strace -o '| grep -w EACCES' /usr/lib/firefox-esr/firefox-bin ... openat(AT_FDCWD, "/usr/share/fonts/truetype/mononoki/.uuid.TMP-lrzetE", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES (Permission denied) openat(AT_FDCWD, "/usr/share/fonts/truetype/wine/.uuid.TMP-p6l2oU", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES (Permission denied) openat(AT_FDCWD, "/usr/share/fonts/woff/mononoki/.uuid.TMP-S9ygla", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES (Permission denied) openat(AT_FDCWD, "/usr/share/fonts/X11/encodings/large/.uuid.TMP-VcWBhq", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES (Permission denied) openat(AT_FDCWD, "/usr/lib/firefox-esr/fonts/.uuid.TMP-uG7neG", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES (Permission denied) ... -- Jakub Wilk
