[AIRFLOW-102] Fix test_complex_template always succeeds
[AIRFLOW-102] Fix test_complex_template always succeeds

Exceptions from on_success_callback are stomped
on, meaning
test_complex_template would never fail.

Rather than follow the "success = True" pattern
(which results in the
lovely-to-track-down error message of
`AssertionError: False is not
true` I instead changed all these to have the
verify method be execute
-- meaning exceptions are propagated unchanged.

Thanks to @sekikn in
https://github.com/apache/incubator-
airflow/pull/2375 for the info to
track down what was going on.

Closes #2375

Closes #3100 from
ashb/template_tests_always_succeed

adamhaney/airflow,Acehaidrey/incubator-airflow,criccomini/airflow,danielvdende/incubator-airflow,lyft/incubator-airflow,bolkedebruin/airflow,Tagar/incubator-airflow,edgarRd/incubator-airflow,nathanielvarona/airflow,wileeam/airflow,apache/airflow,artwr/airflow,wndhydrnt/airflow,malmiron/incubator-airflow,mrkm4ntr/incubator-airflow,wooga/airflow,jgao54/airflow,andyxhadji/incubator-airflow,Tagar/incubator-airflow,nathanielvarona/airflow,danielvdende/incubator-airflow,edgarRd/incubator-airflow,owlabs/incubator-airflow,adamhaney/airflow,wolfier/incubator-airflow,subodhchhabra/airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,DinoCow/airflow,Fokko/incubator-airflow,CloverHealth/airflow,Tagar/incubator-airflow,fenglu-g/incubator-airflow,wolfier/incubator-airflow,danielvdende/incubator-airflow,subodhchhabra/airflow,wileeam/airflow,akosel/incubator-airflow,lyft/incubator-airflow,Acehaidrey/incubator-airflow,edgarRd/incubator-airflow,akosel/incubator-airflow,jgao54/airflow,wooga/airflow,yk5/incubator-airflow,apache/incubator-airflow,dhuang/incubator-airflow,wolfier/incubator-airflow,dhuang/incubator-airflow,wooga/airflow,airbnb/airflow,mistercrunch/airflow,wndhydrnt/airflow,cfei18/incubator-airflow,owlabs/incubator-airflow,spektom/incubator-airflow,bolkedebruin/airflow,apache/airflow,Acehaidrey/incubator-airflow,r39132/airflow,apache/airflow,Tagar/incubator-airflow,cfei18/incubator-airflow,yk5/incubator-airflow,mrkm4ntr/incubator-airflow,nathanielvarona/airflow,lxneng/incubator-airflow,fenglu-g/incubator-airflow,danielvdende/incubator-airflow,yk5/incubator-airflow,subodhchhabra/airflow,danielvdende/incubator-airflow,mrkm4ntr/incubator-airflow,apache/airflow,r39132/airflow,sekikn/incubator-airflow,mtagle/airflow,Fokko/incubator-airflow,wileeam/airflow,wndhydrnt/airflow,apache/incubator-airflow,RealImpactAnalytics/airflow,CloverHealth/airflow,adamhaney/airflow,criccomini/airflow,andyxhadji/incubator-airflow,fenglu-g/incubator-airflow,cfei18/incubator-airflow,mtagle/airflow,wndhydrnt/airflow,dhuang/incubator-airflow,subodhchhabra/airflow,lxneng/incubator-airflow,airbnb/airflow,criccomini/airflow,mrkm4ntr/incubator-airflow,yk5/incubator-airflow,sid88in/incubator-airflow,artwr/airflow,sekikn/incubator-airflow,apache/incubator-airflow,artwr/airflow,spektom/incubator-airflow,nathanielvarona/airflow,malmiron/incubator-airflow,gtoonstra/airflow,mistercrunch/airflow,malmiron/incubator-airflow,akosel/incubator-airflow,sid88in/incubator-airflow,dhuang/incubator-airflow,edgarRd/incubator-airflow,jgao54/airflow,jgao54/airflow,wileeam/airflow,sergiohgz/incubator-airflow,spektom/incubator-airflow,cfei18/incubator-airflow,Acehaidrey/incubator-airflow,sekikn/incubator-airflow,nathanielvarona/airflow,mistercrunch/airflow,mistercrunch/airflow,RealImpactAnalytics/airflow,RealImpactAnalytics/airflow,lyft/incubator-airflow,r39132/airflow,airbnb/airflow,wolfier/incubator-airflow,apache/airflow,bolkedebruin/airflow,criccomini/airflow,gtoonstra/airflow,andyxhadji/incubator-airflow,lxneng/incubator-airflow,mtagle/airflow,DinoCow/airflow,DinoCow/airflow,apache/incubator-airflow,mtagle/airflow,lxneng/incubator-airflow,Fokko/incubator-airflow,owlabs/incubator-airflow,sergiohgz/incubator-airflow,fenglu-g/incubator-airflow,gtoonstra/airflow,lyft/incubator-airflow,cfei18/incubator-airflow,bolkedebruin/airflow,andyxhadji/incubator-airflow,r39132/airflow,cfei18/incubator-airflow,owlabs/incubator-airflow,danielvdende/incubator-airflow,CloverHealth/airflow,bolkedebruin/airflow,adamhaney/airflow,sid88in/incubator-airflow,sekikn/incubator-airflow,artwr/airflow,sergiohgz/incubator-airflow,wooga/airflow,DinoCow/airflow,spektom/incubator-airflow,gtoonstra/airflow,akosel/incubator-airflow,RealImpactAnalytics/airflow,Acehaidrey/incubator-airflow,sid88in/incubator-airflow,airbnb/airflow,Fokko/incubator-airflow,malmiron/incubator-airflow,CloverHealth/airflow,sergiohgz/incubator-airflow,apache/airflow