--install-options in requirements.txt are being applied to the wrong packages

[MarkBird]

Environment

• pip version: 18.0
• Python version: 3.6
• OS: Windows 10

Description
I have the following in requirements.txt:

django-pyodbc-azure==1.11.12.1
rcssmin==1.0.6 --install-option="--without-c-extensions"
rjsmin==1.0.12 --install-option="--without-c-extensions"

on pip 18.0, this will not install, because the django-pyodbc-azure line fails with "Could not find a version that satisfies the requirement"

If I remove the 2 packages with the --install-options options, then django-pyodbc-azure installs fine straight away. I can then restore the 2 packages with --install-options and they install fine as well.

Expected behavior
--install-options should only apply to the line in requirements.txt with the option, not to other lines

How to Reproduce
See description

[chrahunt]

The specific problem here is that:

1. django-pyodbc-azure only publishes wheels
2. Any usage of --install-options within a requirements file disables the use of wheels

So this is essentially the same issue as #4118, just with a different option. Like that one, this is related to #2677.

[pradyunsg]

Closing as a duplicate of #4118.