then-with-Executor
Summary:
Pass an Executor to `then`, which applies only for that callback. This is on
the one hand just a convenience method, but it's a major convenience when it's
needed, because grabbing, storing, and restoring the old Executor in the
middle of a chain is very inconvenient indeed.
Test Plan:
new unit
Reviewed By: jsedgwick@fb.com
Subscribers: robbert, exa, folly-diffs@, jsedgwick, nkgupta, yfeldblum, chalfant, davejwatson
FB internal diff:
D1985475
Signature: t1:
1985475:
1429148056:
0450120263ba8110e8825420cbefe3b1887f7306