/usr/share/avogadro/fragments/alkenes/ is in avogadro-data 1.2.0-1+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/avogadro/fragments/alkenes/2-methylbut-2-ene.cml
/usr/share/avogadro/fragments/alkenes/2-methylbuta-1_3-diene.cml
/usr/share/avogadro/fragments/alkenes/3E-penta-1_3-diene.cml
/usr/share/avogadro/fragments/alkenes/3Z-penta-1_3-diene.cml
/usr/share/avogadro/fragments/alkenes/3Z_3-ethylhepta-1_3-diene.cml
/usr/share/avogadro/fragments/alkenes/E-but-2-ene.cml
/usr/share/avogadro/fragments/alkenes/E-hept-2-ene.cml
/usr/share/avogadro/fragments/alkenes/E-hept-3-ene.cml
/usr/share/avogadro/fragments/alkenes/E-hex-2-ene.cml
/usr/share/avogadro/fragments/alkenes/E-hex-3-ene.cml
/usr/share/avogadro/fragments/alkenes/E-oct-2-ene.cml
/usr/share/avogadro/fragments/alkenes/E-oct-3-ene.cml
/usr/share/avogadro/fragments/alkenes/E-oct-4-ene.cml
/usr/share/avogadro/fragments/alkenes/E-pent-2-ene.cml
/usr/share/avogadro/fragments/alkenes/Z-but-2-ene.cml
/usr/share/avogadro/fragments/alkenes/Z-hept-2-ene.cml
/usr/share/avogadro/fragments/alkenes/Z-hept-3-ene.cml
/usr/share/avogadro/fragments/alkenes/Z-hex-2-ene.cml
/usr/share/avogadro/fragments/alkenes/Z-hex-3-ene.cml
/usr/share/avogadro/fragments/alkenes/Z-oct-2-ene.cml
/usr/share/avogadro/fragments/alkenes/Z-oct-3-ene.cml
/usr/share/avogadro/fragments/alkenes/Z-oct-4-ene.cml
/usr/share/avogadro/fragments/alkenes/Z-pent-2-ene.cml
/usr/share/avogadro/fragments/alkenes/but-1-ene.cml
/usr/share/avogadro/fragments/alkenes/ethene.cml
/usr/share/avogadro/fragments/alkenes/hept-1-ene.cml
/usr/share/avogadro/fragments/alkenes/hex-1-ene.cml
/usr/share/avogadro/fragments/alkenes/oct-1-ene.cml
/usr/share/avogadro/fragments/alkenes/pent-1-ene.cml
/usr/share/avogadro/fragments/alkenes/propene.cml