A key created after the last key, no longer respects the previous key's type.
In this case, all my keys are linear, but when I add another key at the end of my curve, it take the default key type (Clamped Auto), not linear.

repro:
- create a Cube.
- open the AW and create a clip.
- add 2-3 keys over time, select them, and set them to Linear.
- move the current time past the last key and hit the "add key" button...
bug: the newly added keys are not Linear (see attached KeyTypeBug.gif)
expected: the newly added keys are Linear (see attached KeyType_expected.gif)

this is a regression that was introduced in 2017.2

repro in…
Version 2017.3.0a4 (6fb2c314e075)
Branch: animation/weightedTangent/hybridCurve
… and …
Version 2017.3.0a4 (d9117167c918)
Branch: animation/dev
… and …
Version 2017.3.0a4 (a7439e75e570)
Branch: trunk
… and …
Version 2017.2.0b7 (4bc201a72e4a)
Branch: 2017.2/staging

NOT repro in…
Version 2017.1.0p3 (0f0686ba7d25)
Branch: 2017.1/patch-release