Export optimization BREAKS for contacts w/ null values for boolean fields

Pretty sure this fatal error is related to the export optimization code just introduced.

I created two Individual contacts with just first, last name, email and address values. Then I tried to export them and got this fatal error (below). Note that the query is trying to insert quoted empty string values into boolean int fields (eg. do_not_email).

--------- fatal error ---------------------
INSERT INTO civicrm_export_temp (id, civicrm_primary_id,contact_type,contact_sub_type,do_not_email,do_not_phone,do_not_mail,do_not_sms,do_not_trade,is_opt_out,legal_identifier,external_identifier,sort_name,display_name,nick_name,legal_name,image_url,preferred_communication_method,preferred_language,preferred_mail_format,contact_source,first_name,middle_name,last_name,job_title,birth_date,is_deceased,deceased_date,mail_to_household_id,household_name,organization_name,sic_code,user_unique_id,current_employer_id,addressee,email_greeting,postal_greeting,gender,individual_prefix,individual_suffix,current_employer,location_type,street_address,street_number,street_number_suffix,street_name,street_unit,supplemental_address_1,supplemental_address_2,city,postal_code_suffix,postal_code,geo_code_1,geo_code_2,address_name,county,state_province,country,phone,email,on_hold,is_bulkmail,signature_text,signature_html,im_provider,im,openid,world_region,url,groups,tags,notes,phone_type_id,provider_id)
VALUES (1,'102','Individual','','','','','','','','','','Greenberg, Dave','Dave Greenberg','','','','','','Both','','Dave','','Greenberg','','','','','','','','','','','','','','','','','','','330 Upper Terrace','','','','','','','San Francisco','','94117','','','','','CA','United States','','dave@civicrm.org','','','','','','','','America South, Central, North and Caribbean','','','','','','')
[nativecode=1366 ** Incorrect integer value: '' for column 'do_not_email' at row 1]