Revert "Displaying pip list command's packages and versions #5062"

This reverts commit 043fdb7c40.
These tests were part of the PR #5155 but weren't relevant to #5602

src/_pytest/terminal.py

@@ -9,7 +9,6 @@ from __future__ import print_function
 import argparse
 import collections
 import platform
-import subprocess
 import sys
 import time
 from functools import partial
@@ -582,11 +581,6 @@ class TerminalReporter(object):
         ):
             msg += " -- " + str(sys.executable)
         self.write_line(msg)
-        pipe = subprocess.Popen("pip list", shell=True, stdout=subprocess.PIPE).stdout
-        package_msg = pipe.read()
-        package_msg = package_msg[:-2]
-        if package_msg:
-            self.write_line(package_msg)
         lines = self.config.hook.pytest_report_header(
             config=self.config, startdir=self.startdir
         )

testing/test_terminal.py

@@ -279,15 +279,6 @@ class TestTerminal(object):
         tr.rewrite("hey", erase=True)
         assert f.getvalue() == "hello" + "\r" + "hey" + (6 * " ")
 
-    def test_packages_display(self, testdir):
-        testdir.makepyfile(
-            """
-            def test_pass(num):
-                assert 1 == 1"""
-        )
-        result = testdir.runpytest()
-        result.stdout.fnmatch_lines(["*Package        Version              *"])
-
 
 class TestCollectonly(object):
     def test_collectonly_basic(self, testdir):