See <https://lists.gnu.org/archive/html/guix-devel/2019-07/msg00265.html>.
* gnu/packages/patches/evolution-data-server-locales.patch: New file.
* gnu/local.mk: Add it.
* gnu/packages/gnome.scm (evolution-data-server): Replace the
'patch-locale-canonicalization' phase with the new patch.