Repository: pypa/pip

Issue:
Possible typo in warning message
**Environment**

* pip version: master branch, and checked for 19.3.1
* Python version: 3.8.0
* OS: alpine linux (actually, it's a docker image `python:3.8-alpine`)

**Description**
As you see below, the warning message is using terms `--build-options`, `--global-options` and `--install-options` but what pip actually accepts are `--build-option`, `--global-option` and `--install-option`(without `s` at the end).
https://github.com/pypa/pip/blob/e3f9a72a0f80e6328d4657cd9fe525f549b1d1e4/src/pip/_internal/cli/cmdoptions.py#L85-L88

**Expected behavior**
The warning message should say `--build-option`, `--global-option` and `--install-option` to not confuse users.

**How to Reproduce**

1. Create a dummy requirements.txt with `--install-option` specified:
```
pip --install-option="-v"
```
2. Run this command:
```
$ python3 -m pip install -r requirements.txt
```

**Output**

```
/usr/lib/python3/dist-packages/pip/req/req_file.py:150: UserWarning: Disabling all use of wheels due to the use of --build-options / --global-options / --install-options.
  cmdoptions.check_install_build_global(options, opts)
Collecting pip (from -r requirements.txt (line 1))
  Using cached https://files.pythonhosted.org/packages/ce/ea/9b445176a65ae4ba22dce1d93e4b5fe182f953df71a145f557cffaffc1bf/pip-19.3.1.tar.gz
Skipping bdist_wheel for pip, due to binaries being disabled for it.
Installing collected packages: pip
  Running setup.py install for pip ... done
Successfully installed pip-19.3.1
```



Discussion:

Resolving patch:
diff --git a/src/pip/_internal/cli/cmdoptions.py b/src/pip/_internal/cli/cmdoptions.py
--- a/src/pip/_internal/cli/cmdoptions.py
+++ b/src/pip/_internal/cli/cmdoptions.py
@@ -83,8 +83,8 @@ def getname(n):
         control = options.format_control
         control.disallow_binaries()
         warnings.warn(
-            'Disabling all use of wheels due to the use of --build-options '
-            '/ --global-options / --install-options.', stacklevel=2,
+            'Disabling all use of wheels due to the use of --build-option '
+            '/ --global-option / --install-option.', stacklevel=2,
         )
 
 
diff --git a/src/pip/_internal/wheel_builder.py b/src/pip/_internal/wheel_builder.py
--- a/src/pip/_internal/wheel_builder.py
+++ b/src/pip/_internal/wheel_builder.py
@@ -345,7 +345,7 @@ def _build_one_pep517(
         if self.build_options:
             # PEP 517 does not support --build-options
             logger.error('Cannot build wheel for %s using PEP 517 when '
-                         '--build-options is present' % (req.name,))
+                         '--build-option is present' % (req.name,))
             return None
         try:
             logger.debug('Destination directory: %s', tempd)


Test patch:
diff --git a/tests/functional/test_pep517.py b/tests/functional/test_pep517.py
--- a/tests/functional/test_pep517.py
+++ b/tests/functional/test_pep517.py
@@ -214,4 +214,4 @@ def test_pep517_and_build_options(script, tmpdir, data, common_wheels):
         expect_error=True
     )
     assert 'Cannot build wheel' in result.stderr
-    assert 'when --build-options is present' in result.stderr
+    assert 'when --build-option is present' in result.stderr