tree 29878e0b97fabf20184355a559e55488cd69b9ae
parent 716f049a7b91a8f3a4632c367d9534d1d9190a81
author Sameer Agarwal <sameeragarwal@google.com> 1472771106 -0700
committer Sameer Agarwal <sameeragarwal@google.com> 1472771106 -0700

FindWithDefault returns by value rather than reference.

Returning by reference leads to lifetime issues with the default
value which may go out of scope by the time it is used.

Thanks to @Ardavel for reporting this, as this causes graph_test
to fail on VS2015x64.

https://github.com/ceres-solver/ceres-solver/issues/216

Change-Id: I596481219cfbf7622d49a6511ea29193b82c8ba3