Silence warning from MySQL::Error object in test
Silence warning from MySQL::Error object in test

When running Active Record MySQL test, this warning is printed in the
console:

    warning: instance variable errno not initialized

It turns out that this is a warning from `mysql` gem in MySQL::Error
object. However, since the `mysql` gem is no longer maintained, and
there won't be a newer version, it make sense for us to just silence
this warning to make the output cleaner.

sergey-alekseev/rails,pvalena/rails,illacceptanything/illacceptanything,maicher/rails,maicher/rails,sealocal/rails,Vasfed/rails,jeremy/rails,lcreid/rails,prathamesh-sonpatki/rails,felipecvo/rails,eileencodes/rails,yahonda/rails,yalab/rails,esparta/rails,utilum/rails,bogdanvlviv/rails,palkan/rails,illacceptanything/illacceptanything,mohitnatoo/rails,georgeclaghorn/rails,iainbeeston/rails,kmcphillips/rails,kachick/rails,lcreid/rails,fabianoleittes/rails,palkan/rails,illacceptanything/illacceptanything,yhirano55/rails,coreyward/rails,notapatch/rails,assain/rails,BlakeWilliams/rails,yawboakye/rails,assain/rails,gfvcastro/rails,mechanicles/rails,deraru/rails,kmayer/rails,sealocal/rails,jeremy/rails,kamipo/rails,illacceptanything/illacceptanything,prathamesh-sonpatki/rails,felipecvo/rails,xlymian/rails,kirs/rails-1,stefanmb/rails,flanger001/rails,rafaelfranca/omg-rails,pschambacher/rails,fabianoleittes/rails,vipulnsward/rails,baerjam/rails,betesh/rails,mijoharas/rails,yasslab/railsguides.jp,MichaelSp/rails,flanger001/rails,riseshia/railsguides.kr,printercu/rails,kmayer/rails,palkan/rails,mechanicles/rails,Envek/rails,arunagw/rails,amoody2108/TechForJustice,utilum/rails,bradleypriest/rails,lucasmazza/rails,yalab/rails,Envek/rails,rails/rails,Vasfed/rails,Stellenticket/rails,schuetzm/rails,Sen-Zhang/rails,koic/rails,bradleypriest/rails,kirs/rails-1,riseshia/railsguides.kr,kachick/rails,illacceptanything/illacceptanything,illacceptanything/illacceptanything,lucasmazza/rails,ledestin/rails,mathieujobin/reduced-rails-for-travis,sealocal/rails,rails/rails,iainbeeston/rails,BlakeWilliams/rails,amoody2108/TechForJustice,betesh/rails,iainbeeston/rails,kddeisz/rails,yasslab/railsguides.jp,koic/rails,gauravtiwari/rails,illacceptanything/illacceptanything,voray/rails,betesh/rails,repinel/rails,illacceptanything/illacceptanything,pschambacher/rails,BlakeWilliams/rails,shioyama/rails,Erol/rails,kddeisz/rails,felipecvo/rails,shioyama/rails,arunagw/rails,kachick/rails,yawboakye/rails,gavingmiller/rails,iainbeeston/rails,fabianoleittes/rails,Sen-Zhang/rails,koic/rails,illacceptanything/illacceptanything,Erol/rails,riseshia/railsguides.kr,coreyward/rails,Envek/rails,marklocklear/rails,yahonda/rails,tgxworld/rails,tijwelch/rails,kaspth/rails,jeremy/rails,vassilevsky/rails,ngpestelos/rails,repinel/rails,printercu/rails,samphilipd/rails,Stellenticket/rails,pvalena/rails,tgxworld/rails,joonyou/rails,odedniv/rails,ledestin/rails,rafaelfranca/omg-rails,kirs/rails-1,tgxworld/rails,untidy-hair/rails,mtsmfm/railstest,ttanimichi/rails,MichaelSp/rails,voray/rails,kenta-s/rails,repinel/rails,palkan/rails,matrinox/rails,joonyou/rails,baerjam/rails,richseviora/rails,shioyama/rails,gfvcastro/rails,pvalena/rails,gavingmiller/rails,gcourtemanche/rails,yhirano55/rails,arunagw/rails,gcourtemanche/rails,bolek/rails,hanystudy/rails,eileencodes/rails,mohitnatoo/rails,illacceptanything/illacceptanything,illacceptanything/illacceptanything,Erol/rails,tjschuck/rails,rossta/rails,baerjam/rails,mijoharas/rails,kaspth/rails,Spin42/rails,georgeclaghorn/rails,illacceptanything/illacceptanything,jeremy/rails,rbhitchcock/rails,rafaelfranca/omg-rails,Erol/rails,Spin42/rails,rossta/rails,arjes/rails,travisofthenorth/rails,Edouard-chin/rails,tgxworld/rails,kddeisz/rails,bogdanvlviv/rails,mtsmfm/railstest,notapatch/rails,MSP-Greg/rails,tijwelch/rails,georgeclaghorn/rails,starknx/rails,travisofthenorth/rails,esparta/rails,hanystudy/rails,rbhitchcock/rails,mtsmfm/rails,bradleypriest/rails,prathamesh-sonpatki/rails,mohitnatoo/rails,untidy-hair/rails,rossta/rails,mechanicles/rails,illacceptanything/illacceptanything,alecspopa/rails,ttanimichi/rails,flanger001/rails,esparta/rails,repinel/rails,elfassy/rails,odedniv/rails,lcreid/rails,EmmaB/rails-1,vipulnsward/rails,Vasfed/rails,Envek/rails,Stellenticket/rails,alecspopa/rails,Spin42/rails,88rabbit/newRails,kddeisz/rails,pvalena/rails,alecspopa/rails,samphilipd/rails,betesh/rails,mohitnatoo/rails,rails/rails,kamipo/rails,tjschuck/rails,mtsmfm/rails,assain/rails,starknx/rails,deraru/rails,vassilevsky/rails,arjes/rails,EmmaB/rails-1,coreyward/rails,fabianoleittes/rails,sergey-alekseev/rails,MSP-Greg/rails,arjes/rails,yalab/rails,odedniv/rails,yasslab/railsguides.jp,assain/rails,schuetzm/rails,aditya-kapoor/rails,printercu/rails,baerjam/rails,untidy-hair/rails,notapatch/rails,elfassy/rails,mathieujobin/reduced-rails-for-travis,bolek/rails,utilum/rails,MichaelSp/rails,Edouard-chin/rails,brchristian/rails,mtsmfm/rails,tjschuck/rails,xlymian/rails,elfassy/rails,tijwelch/rails,deraru/rails,yawboakye/rails,yalab/rails,untidy-hair/rails,Sen-Zhang/rails,gfvcastro/rails,tjschuck/rails,hanystudy/rails,gauravtiwari/rails,deraru/rails,MSP-Greg/rails,schuetzm/rails,stefanmb/rails,yahonda/rails,gavingmiller/rails,xlymian/rails,88rabbit/newRails,yahonda/rails,kenta-s/rails,BlakeWilliams/rails,yasslab/railsguides.jp,voray/rails,stefanmb/rails,utilum/rails,arunagw/rails,vipulnsward/rails,kaspth/rails,EmmaB/rails-1,eileencodes/rails,riseshia/railsguides.kr,88rabbit/newRails,notapatch/rails,Stellenticket/rails,matrinox/rails,rbhitchcock/rails,ledestin/rails,kmayer/rails,kenta-s/rails,richseviora/rails,yhirano55/rails,ngpestelos/rails,sergey-alekseev/rails,gfvcastro/rails,brchristian/rails,marklocklear/rails,joonyou/rails,Vasfed/rails,Edouard-chin/rails,aditya-kapoor/rails,ngpestelos/rails,mechanicles/rails,bolek/rails,gauravtiwari/rails,joonyou/rails,brchristian/rails,vassilevsky/rails,illacceptanything/illacceptanything,travisofthenorth/rails,aditya-kapoor/rails,esparta/rails,vipulnsward/rails,bogdanvlviv/rails,shioyama/rails,mathieujobin/reduced-rails-for-travis,samphilipd/rails,ttanimichi/rails,kmcphillips/rails,richseviora/rails,pschambacher/rails,illacceptanything/illacceptanything,amoody2108/TechForJustice,marklocklear/rails,yhirano55/rails,schuetzm/rails,MSP-Greg/rails,flanger001/rails,kmcphillips/rails,mtsmfm/railstest,travisofthenorth/rails,rails/rails,Edouard-chin/rails,prathamesh-sonpatki/rails,printercu/rails,eileencodes/rails,mijoharas/rails,maicher/rails,starknx/rails,kmcphillips/rails,lcreid/rails,aditya-kapoor/rails,lucasmazza/rails,yawboakye/rails,matrinox/rails,georgeclaghorn/rails,bogdanvlviv/rails,kamipo/rails,gcourtemanche/rails