Release 1.12 Install torch from test channel, Pin builder and xla repo

Author: atalman

Diff for: .circleci/scripts/binary_checkout.sh

@@ -62,7 +62,7 @@ git --no-pager log --max-count 1
 popd
 
 # Clone the Builder master repo
-retry git clone -q https://github.com/pytorch/builder.git "$BUILDER_ROOT"
+retry git clone -q https://github.com/pytorch/builder.git -b release/1.12 "$BUILDER_ROOT"
 pushd "$BUILDER_ROOT"
 echo "Using builder from "
 git --no-pager log --max-count 1

Diff for: .jenkins/pytorch/common_utils.sh

@@ -99,6 +99,6 @@ function checkout_install_torchvision() {
 
 function clone_pytorch_xla() {
   if [[ ! -d ./xla ]]; then
-    git clone --recursive --quiet https://github.com/pytorch/xla.git
+    git clone --recursive -b release/1.12 https://github.com/pytorch/xla.git
   fi
 }

Diff for: .jenkins/pytorch/test.sh

@@ -460,7 +460,7 @@ test_forward_backward_compatibility() {
   python -m venv venv
   # shellcheck disable=SC1091
   . venv/bin/activate
-  pip_install --pre torch -f https://download.pytorch.org/whl/nightly/cpu/torch_nightly.html
+  pip_install --pre torch -f https://download.pytorch.org/whl/test/cpu/torch_test.html
   pip show torch
   python dump_all_function_schemas.py --filename nightly_schemas.txt
   # FC: verify newmodel can be load with old code.