[pkgsrc] "make install" : Malformed conditional (${_USE_DESTDIR} != "no")

I try to install textproc/py-elementtree but:

preston:pkgsrc/textproc/py-elementtree % make install
make: "../../lang/python/../../lang/python/extension.mk" line 25: Malformed conditional (${_USE_DESTDIR} != "no")
make: "../../lang/python/../../lang/python/extension.mk" line 38: if-less endif
make: "../../lang/python/../../lang/python/extension.mk" line 38: Need an operator
make: Fatal errors encountered -- cannot continue

make: stopped in /usr/pkgsrc/textproc/py-elementtree

Indeed, checking /usr/pkgsrc/lang/python/extension.mk, I see strange
things such as ".endif" without ".if":

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.if ${_USE_DESTDIR} != "no"
_PYSETUPINSTALLARGS+=   --root=${DESTDIR:Q}
.endif
PY_PATCHPLIST?=         yes
PYSETUPSUBDIR?=         #empty

do-build:
        (cd ${WRKSRC}/${PYSETUPSUBDIR} && ${SETENV} ${MAKE_ENV} ${PYTHONBIN} \
         ${PYSETUP} build ${PYSETUPBUILDARGS})

do-install:
        (cd ${WRKSRC}/${PYSETUPSUBDIR} && ${SETENV} ${MAKE_ENV} ${PYTHONBIN} \
         ${PYSETUP} "install" ${_PYSETUPINSTALLARGS})
.endif

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NetBSD 3.0.1
pkg_comp-1.29       Build packages inside a chroot jail
pkg_install-20060720 Package management and administration tools for pkgsrc