sam build fails for python3.7 functions with pip==19.3 installed

Description

with aws-sam-cli==0.22.0 and pip==19.3 installed sam build fails:

Building resource 'TestFunction'
Running PythonPipBuilder:ResolveDependencies

Build Failed
Error: PythonPipBuilder:ResolveDependencies - Traceback (most recent call last):
  File "<string>", line 1, in <module>
TypeError: 'module' object is not callabl

Steps to reproduce

template.yml

Transform: AWS::Serverless-2016-10-31
Resources:
  TestFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: app.handler
      Runtime: python3.7

requirements.txt

requests

commands to reproduce

pip install pip==19.3 aws-sam-cli==0.22.0
sam build

Observed result

command output with --debug flag set.

Using SAM Template at /x/x/x/x/template.yml
Telemetry endpoint configured to be https://aws-serverless-tools-telemetry.us-west-2.amazonaws.com/metrics
'build' command is called
No Parameters detected in the template
1 resources found in the template
Found Serverless function with name='TestFunction' and CodeUri='.'
Building resource 'TestFunction'
Loading workflow module 'aws_lambda_builders.workflows'
Registering workflow 'PythonPipBuilder' with capability 'Capability(language='python', dependency_manager='pip', application_framework=None)'
Registering workflow 'NodejsNpmBuilder' with capability 'Capability(language='nodejs', dependency_manager='npm', application_framework=None)'
Registering workflow 'RubyBundlerBuilder' with capability 'Capability(language='ruby', dependency_manager='bundler', application_framework=None)'
Registering workflow 'GoDepBuilder' with capability 'Capability(language='go', dependency_manager='dep', application_framework=None)'
Registering workflow 'GoModulesBuilder' with capability 'Capability(language='go', dependency_manager='modules', application_framework=None)'
Registering workflow 'JavaGradleWorkflow' with capability 'Capability(language='java', dependency_manager='gradle', application_framework=None)'
Registering workflow 'JavaMavenWorkflow' with capability 'Capability(language='java', dependency_manager='maven', application_framework=None)'
Registering workflow 'DotnetCliPackageBuilder' with capability 'Capability(language='dotnet', dependency_manager='cli-package', application_framework=None)'
Found workflow 'PythonPipBuilder' to support capabilities 'Capability(language='python', dependency_manager='pip', application_framework=None)'
Running workflow 'PythonPipBuilder'
Running PythonPipBuilder:ResolveDependencies
calling pip download -r /home/ttb/axsemantics/code/eddaplayground/requirements.txt --dest /tmp/tmp4wnow8ph
PythonPipBuilder:ResolveDependencies failed
Traceback (most recent call last):
  File "/home/ttb/.local/share/virtualenvs/eddaplayground-9KTS0LqI/lib/python3.7/site-packages/aws_lambda_builders/workflows/python_pip/actions.py", line 39, in execute
    requirements_path=self.manifest_path
  File "/home/ttb/.local/share/virtualenvs/eddaplayground-9KTS0LqI/lib/python3.7/site-packages/aws_lambda_builders/workflows/python_pip/packager.py", line 143, in build_dependencies
    requirements_path, artifacts_dir_path, scratch_dir_path)
  File "/home/ttb/.local/share/virtualenvs/eddaplayground-9KTS0LqI/lib/python3.7/site-packages/aws_lambda_builders/workflows/python_pip/packager.py", line 209, in build_site_packages
    scratch_directory, requirements_filepath)
  File "/home/ttb/.local/share/virtualenvs/eddaplayground-9KTS0LqI/lib/python3.7/site-packages/aws_lambda_builders/workflows/python_pip/packager.py", line 234, in _download_dependencies
    requirements_filename, directory)
  File "/home/ttb/.local/share/virtualenvs/eddaplayground-9KTS0LqI/lib/python3.7/site-packages/aws_lambda_builders/workflows/python_pip/packager.py", line 330, in _download_all_dependencies
    self._pip.download_all_dependencies(requirements_filename, directory)
  File "/home/ttb/.local/share/virtualenvs/eddaplayground-9KTS0LqI/lib/python3.7/site-packages/aws_lambda_builders/workflows/python_pip/packager.py", line 632, in download_all_dependencies
    raise PackageDownloadError(error)
aws_lambda_builders.workflows.python_pip.packager.PackageDownloadError: Traceback (most recent call last):
  File "<string>", line 1, in <module>
TypeError: 'module' object is not callable


During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/ttb/.local/share/virtualenvs/eddaplayground-9KTS0LqI/lib/python3.7/site-packages/aws_lambda_builders/workflow.py", line 248, in run
    action.execute()
  File "/home/ttb/.local/share/virtualenvs/eddaplayground-9KTS0LqI/lib/python3.7/site-packages/aws_lambda_builders/workflows/python_pip/actions.py", line 42, in execute
    raise ActionFailedError(str(ex))
aws_lambda_builders.actions.ActionFailedError: Traceback (most recent call last):
  File "<string>", line 1, in <module>
TypeError: 'module' object is not callable


Build Failed
Sending Telemetry: {'metrics': [{'commandRun': {'awsProfileProvided': False, 'debugFlagProvided': True, 'region': '', 'commandName': 'sam build', 'duration': 347, 'exitReason': 'UserException', 'exitCode': 1, 'requestId': 'b01b8130-a7a5-4176-8301-0e0b5a021a34', 'installationId': '8cd66ae9-04d8-4819-94c9-8b15f5cf52b7', 'sessionId': 'd530a4e3-c3aa-4bf3-a830-01f00e264479', 'executionEnvironment': 'CLI', 'pyversion': '3.7.4', 'samcliVersion': '0.22.0'}}]}
HTTPSConnectionPool(host='aws-serverless-tools-telemetry.us-west-2.amazonaws.com', port=443): Read timed out. (read timeout=0.1)
Error: PythonPipBuilder:ResolveDependencies - Traceback (most recent call last):
  File "<string>", line 1, in <module>
TypeError: 'module' object is not callable

Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

1. OS: fedora 30
2. sam --version: 0.22.0

[Konchannel]

I had the same error with the same pip version. It was solved by lowering the version of pip. pip install pip==19.2.3

[jfuss]

This was released in v0.23.0.

Closing.