I too have tripped across the bug documented in the following tread, I don’t know if it has been officially filed or not.
https://forum.mythtv.org/viewtopic.php?f=2&t=1205&start=15

I recently upgraded to Ubuntu 16.04 and mythtv v0.28 v0.28-98-g0890206 from Ubuntu 14.04 and mythtv 0.27.  The upgrade when smoothly, except my user job stopped working.  My job is similar to transcode-h264.py located here: https://www.mythtv.org/wiki/Transcode_Mpeg2_to_H264

The script stops at the rec.update() command will an error.  I hacked the script with the following workaround suggested by the forum posting and it now runs.
 
.
.
#the following line is hack to fix this bug https://forum.mythtv.org/viewtopic.php?f=2&t=1205
rec.bookmarkupdate=starttime
.
rec.update()
.
.

Interacting with python directly gives the exact point of failure
craig-nuc.craig 4098> python
Python 2.7.12 (default, Nov 19 2016, 06:48:10)
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from MythTV import Job, Recorded, System, MythDB, findfile, MythError, MythLog, datetime
>>> from optparse import OptionParser
>>> from glob import glob
>>> from shutil import copyfile
>>> import sys
>>> import os
>>> import errno
>>> import time
>>> db = MythDB()
>>> job = Job(2057, db=db)
>>> chanid = job.chanid
>>> starttime = job.starttime
>>> rec = Recorded((chanid, starttime), db=db)
>>> rec.update()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/MythTV/database.py", line 429, in update
    self._push()
  File "/usr/lib/python2.7/dist-packages/MythTV/dataheap.py", line 351, in _push
    DBDataWrite._push(self)
  File "/usr/lib/python2.7/dist-packages/MythTV/database.py", line 408, in _push
    % (self._table, format_string, self._where), sql_values)
  File "/usr/lib/python2.7/dist-packages/MythTV/_conn_mysqldb.py", line 71, in execute
    raise MythDBError(MythDBError.DB_RAW, e.args)
MythTV.exceptions.MythDBError: MySQL error 1292: Incorrect datetime value: '0' for column 'bookmarkupdate' at row 1
>>>

Has this bug been filed?  I look forward to removing the hack from my user job.

craig-nuc.craig 4082> mythbackend --version
Please attach all output as a file in bug reports.
MythTV Version : v0.28-98-g0890206
MythTV Branch : fixes/0.28
Network Protocol : 88
Library API : 0.28.20161120-1
QT Version : 5.5.1
Options compiled in:
 linux profile use_hidesyms using_alsa using_oss using_pulse using_pulseoutput using_backend using_bindings_perl using_bindings_python using_bindings_php using_crystalhd using_dvb using_firewire using_frontend using_hdhomerun using_vbox using_ceton using_hdpvr using_ivtv using_joystick_menu using_libcec using_libcrypto using_libdns_sd using_libfftw3 using_libxml2 using_lirc using_mheg using_opengl using_opengl_video using_opengl_themepainter using_qtwebkit using_qtscript using_qtdbus using_sdl using_taglib using_v4l2 using_x11 using_xrandr using_xv using_profiletype using_bindings_perl using_bindings_python using_bindings_php using_freetype2 using_mythtranscode using_opengl using_vaapi using_vdpau using_ffmpeg_threads using_mheg using_libass using_libxml2