Raise error for unsupported lock mode in Dataset#lock on PostgreSQL
Raise error for unsupported lock mode in Dataset#lock on PostgreSQL

nju520/sequel,nju520/sequel,Marketcircle/sequel,seeARMS/sequel,t-morgan/sequel,offshore-safety/sequel,freshpay/sequel,yazshel/sequel,yazshel/sequel,uhoh-itsmaciek/sequel,pfarrell/sequel,davidbegin/sequel,gferguson-gd/sequel,knut2/sequel,offshore-safety/sequel,reubano/sequel,gferguson-gd/sequel,mpalmer/sequel,pfarrell/sequel,uhoh-itsmaciek/sequel,seeARMS/sequel,beni55/sequel,nicohvi/sequel,knut2/sequel,reubano/sequel,mpalmer/sequel,dennis-d/custom_sequel,dennis-d/custom_sequel,chef/sequel,beni55/sequel,offshore-safety/sequel,t-morgan/sequel,freshpay/sequel,bigfix/sequel,nicohvi/sequel,davidbegin/sequel