Fixes <https://issues.guix.gnu.org/58221>.
Reported by Tobias Kortkamp <tobias.kortkamp@gmail.com>.
Previously, if NAUTILUS_EXTENSION_PATH contained the same directory
several times, Nautilus could end up loading the same extension a second
time and crash. This patch ensures that each extension cannot be loaded
more than once.
* gnu/packages/patches/nautilus-extension-search-path.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/gnome.scm (nautilus)[source]: Use it.
[arguments]: Remove 'make-extensible' phase.
