Merge pull request tensorflow#39525 from tensorflow/mm-fix-major-api-…

…version

Fix tests when `tf._major_api_version` does not exist

Merge pull request tensorflow#39441 from terryheo/r1.15-fix-rpi-build

Switch Raspberry Pi building to unofficial GCC 6.5 toolchain

Merge pull request tensorflow#39355 from tensorflow-jenkins/relnotes-…

…2.0.2-25649

Update release notes for TensorFlow 2.0.2

Update version numbers to 2.2.0

Merge pull request tensorflow#39032 from tensorflow/mm-update-estimat…

…or-hash

Use Estimator 2.2.0

Merge pull request tensorflow#37312 from tensorflow-jenkins/relnotes-…

…2.2.0rc0-16655

Update release notes for TensorFlow 2.2.0

Merge pull request tensorflow#37919 from reedwm/none_grad_fix

2.2-rc2 cherry-pick request: Fix crash in Model.fit() if a gradient is None

Merge pull request tensorflow#37704 from geetachavan1/cherrypicks_RB9MM

[r2.2:Cherrypick] Remove the trailing 'm' , since the tag for py38 is not cp38m but cp38.

Merge pull request tensorflow#37486 from tensorflow/mm-r2.2-debug-win…

…-build

Debug windows builds, add `-s` bazel flag

Merge pull request tensorflow#36215 from tensorflow-jenkins/version-n…

…umbers-1.15.2-8214

Update version numbers for TensorFlow 1.15.2