  We report the discovery of the fifth self-lensing binary in which a low-mass
white dwarf (WD) gravitationally magnifies its 15th magnitude G-star companion,
KIC 8145411, during eclipses. The system was identified from a pair of such
self-lensing events in the Kepler photometry, and was followed up with the
Tillinghast Reflector Echelle Spectrograph (TRES) on the 1.5m telescope at the
Fred Lawrence Whipple Observatory and the High-Dispersion Spectrograph (HDS) on
the Subaru 8.2m telescope. A joint analysis of the TRES radial velocities, the
HDS spectrum, and the Kepler photometry of the primary star determines the WD
mass $0.20\pm0.01\,M_\odot$, orbital semi-major axis
$1.28\pm0.03\,\mathrm{au}$, and orbital eccentricity $0.14\pm0.02$. Because
such extremely low-mass WDs cannot be formed in isolation within the age of the
Galaxy, their formation is believed to involve binary interactions that
truncated evolution of the WD progenitor. However, the observed orbit of the
KIC 8145411 system is at least ten times wider than required for this scenario
to work. The presence of this system in the Kepler sample, along with its
similarities to field blue straggler binaries presumably containing WDs, may
suggest that some 10% of post-AGB binaries with Sun-like primaries contain such
anomalous WDs.
