debian (1.2.22-3~bpo8+1) package build failure

I'm trying to test a trivial patch to set FD_CLOEXEC on the
flintlock lockfd when using F_OFD_SETLK and am running into a
build failure even in an unpatched state.

This is on a Debian jessie amd64 system building the
jessie-backports version.  The stable version (1.2.19-1+deb8u1)
works and builds fine using the same commands, however I also
encountered a similar build problem in a sid chroot with
1.2.23-1

$ debian/rules build && fakeroot debian/rules binary
: ...ends with the following:

dh_install --sourcedir=debian/tmp --fail-missing
dh_install: libxapian22 missing files (usr/lib/*/libxapian.so.*), aborting
debian/rules:171: recipe for target 'install-stamp' failed
make: *** [install-stamp] Error 20

There's a couple of possibly-relevant lines near the top:

libtool: warning: 'libxapian.la' has not been installed in '/usr/lib'
libtool: install: /usr/bin/install -c bin/.libs/xapian-check /tmp/xapian-core-1.
2.22/debian/tmp/usr/bin/xapian-check
libtool: warning: 'libxapian.la' has not been installed in '/usr/lib'
libtool: install: /usr/bin/install -c bin/.libs/xapian-compact /tmp/xapian-core-
1.2.22/debian/tmp/usr/bin/xapian-compact
libtool: warning: 'libxapian.la' has not been installed in '/usr/lib'
libtool: install: /usr/bin/install -c bin/.libs/xapian-inspect /tmp/xapian-core-
1.2.22/debian/tmp/usr/bin/xapian-inspect
libtool: warning: 'libxapian.la' has not been installed in '/usr/lib'

Not sure what's wrong, yet...  I'm wondering of anybody else
has seen this.

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