Fix crash when sys.stdin is None (#7118)

news/7118.bugfix

@@ -0,0 +1 @@
+Fix a crash when ``sys.stdin`` is set to ``None``, such as on AWS Lambda.

news/7119.bugfix

@@ -0,0 +1 @@
+Fix a crash when ``sys.stdin`` is set to ``None``, such as on AWS Lambda.

src/pip/_internal/utils/misc.py

@@ -864,3 +864,10 @@ def protect_pip_from_modification_on_windows(modifying_pip):
             'To modify pip, please run the following command:\n{}'
             .format(" ".join(new_command))
         )
+
+
+def is_console_interactive():
+    # type: () -> bool
+    """Is this console interactive?
+    """
+    return sys.stdin is not None and sys.stdin.isatty()

src/pip/_internal/vcs/subversion.py

@@ -6,11 +6,11 @@ from __future__ import absolute_import
 import logging
 import os
 import re
-import sys
 
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import (
     display_path,
+    is_console_interactive,
     rmtree,
     split_auth_from_netloc,
 )
@@ -188,7 +188,7 @@ class Subversion(VersionControl):
     def __init__(self, use_interactive=None):
         # type: (bool) -> None
         if use_interactive is None:
-            use_interactive = sys.stdin.isatty()
+            use_interactive = is_console_interactive()
         self.use_interactive = use_interactive
 
         # This member is used to cache the fetched version of the current

tests/unit/test_utils.py

@@ -39,6 +39,7 @@ from pip._internal.utils.misc import (
     get_prog,
     hide_url,
     hide_value,
+    is_console_interactive,
     normalize_path,
     normalize_version_info,
     parse_netloc,
@@ -971,3 +972,18 @@ def test_make_setuptools_shim_args__unbuffered_output(unbuffered_output):
         unbuffered_output=unbuffered_output
     )
     assert ('-u' in args) == unbuffered_output
+
+
+@pytest.mark.parametrize('isatty,no_stdin,expected', [
+    (True, False, True),
+    (False, False, False),
+    (True, True, False),
+    (False, True, False),
+])
+def test_is_console_interactive(monkeypatch, isatty, no_stdin, expected):
+    monkeypatch.setattr(sys.stdin, 'isatty', Mock(return_value=isatty))
+
+    if no_stdin:
+        monkeypatch.setattr(sys, 'stdin', None)
+
+    assert is_console_interactive() is expected