pip broken, reinstall doesn't work. EC2

first, which pip is not going to return the same result as sudo which pip, so you should check that out first.

you may also consider not running pip as sudo at all. Is it acceptable & safe to run pip install under sudo?

second, can you try this:

easy_install --upgrade pip

if you get an error here (regarding pip's wheel support), try this, then run the above command again:

easy_install -U setuptools

I fixed the same error ("The 'pip==6.1.1' distribution was not found") by using the tip of Wesm :

$> which pip && sudo which pip
/usr/local/bin/pip
/usr/bin/pip

So, it seels that "pip" of average user and of root are not the same. Will fix it later.

Then I ran "sudo easy_install --upgrade pip" => succeed

Then I used "sudo /usr/local/bin/pip install " and it works.

Some additional information for anyone who is also stuck on the same issue:-

Running commands with sudo searches for the command in usr/bin directory. One way to solve this issue is to specify the complete path to the command while using sudo as commented by @Cissoid in the question's comment section

Or

...what you can do is create a symbolic link(sym link) to that command in the usr/bin directory using ln command.

$> ln -s /usr/local/bin/pip /usr/bin/pip

The syntax is:-

$> ln -s /path/to/file /path/to/link