Part of build.log with error

err-build.log (text/plain), 520 bytes, created by Jiri Netolicky on 2019-03-28 08:41:30 UTC

error: failed to calculate checksum of: /var/tmp/portage/www-client/firefox-66.0.2/work/firefox-66.0.2/third_party/rust/packed_simd/LICENSE-APACHE
Caused by:
  No such file or directory (os error 2)
gmake[4]: *** [/var/tmp/portage/www-client/firefox-66.0.2/work/firefox-66.0.2/config/rules.mk:1027: force-cargo-library-build] Error 101
gmake[3]: *** [/var/tmp/portage/www-client/firefox-66.0.2/work/firefox-66.0.2/config/recurse.mk:74: toolkit/library/rust/target] Error 2
gmake[3]: *** Waiting for unfinished jobs....