Fix pytorch branch ref to run userbenchmark instruction-count (#1623)
Summary:
The pytorch github default branch is recently changed to main. The userbenchmark instruction-count references to the master branch, and so running the benchmark fails git clone with error that remote branch master not found in upstream origin.
Error:
```
Traceback (most recent call last):
File "/workspace/benchmark/run_benchmark.py", line 36, in <module>
run()
File "/workspace/benchmark/run_benchmark.py", line 30, in run
benchmark.run(bm_args)
File "/workspace/benchmark/userbenchmark/instruction-count/__init__.py", line 91, in run
checkout_pytorch_repo(args.pytorch_src, args.pytorch_branch)
File "/workspace/benchmark/userbenchmark/instruction-count/__init__.py", line 57, in checkout_pytorch_repo
git.Repo.clone_from(PYTORCH_SRC_URL, pytorch_repo, depth=1, branch=pytorch_branch)
File "/opt/conda/lib/python3.10/site-packages/git/repo/base.py", line 1325, in clone_from
return cls._clone(
File "/opt/conda/lib/python3.10/site-packages/git/repo/base.py", line 1234, in _clone
finalize_process(proc, stderr=stderr)
File "/opt/conda/lib/python3.10/site-packages/git/util.py", line 419, in finalize_process
proc.wait(**kwargs)
File "/opt/conda/lib/python3.10/site-packages/git/cmd.py", line 604, in wait
raise GitCommandError(remove_password_if_present(self.args), status, errstr)
git.exc.GitCommandError: Cmd('git') failed due to: exit code(128)
cmdline: git clone -v --depth=1 --branch=master -- https://github.com/pytorch/pytorch.git /workspace/benchmark/.userbenchmark/instruction-count/run-20230508150051
stderr: 'Cloning into '/workspace/benchmark/.userbenchmark/instruction-count/run-20230508150051'...
warning: Could not find remote branch master to clone.
fatal: Remote branch master not found in upstream origin
```
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1623
Reviewed By: aaronenyeshi
Differential Revision: D45659624
Pulled By: xuzhao9
fbshipit-source-id: e109c2437badfd1db95badd71ba459afd42fe938