[fixup] Fix leaked temporary pip $HOME on exit

Fixup "711d8710"

src/zc/buildout/easy_install.py

@@ -18,7 +18,6 @@ It doesn't install scripts.  It uses setuptools and requires it to be
 installed.
 """
 
-import atexit
 import copy
 import distutils.errors
 import distutils.sysconfig
@@ -1846,21 +1845,18 @@ try:
 except ImportError:
     PIP_HAS_PYTHON_VERSION_WARNING_OPTION = False
 
-# Temporary HOME with .pydistutils.cfg to disable setup_requires
-pip_pydistutils_home = tempfile.mkdtemp('pip-pydistutils-home')
-with open(os.path.join(pip_pydistutils_home, '.pydistutils.cfg'), 'w') as f:
-    f.write("[easy_install]\n"
-            "index-url = file:///dev/null")
-atexit.register(zc.buildout.rmtree.rmtree, pip_pydistutils_home)
 
 def call_pip_command(command, operand, options, verbosity=-10):
     """
     Call `pip <command...> <operand...>` from a subprocess
     with appropriate options and environment.
     """
+    cleanup = []
+    try:
         env = os.environ.copy()
         pythonpath = pip_path[:]
-    pythonpath.extend(env.get(k) for k in ('PYTHONPATH', 'PYTHONEXTRAPATH'))
+        pythonpath.extend(
+            env.get(k) for k in ('PYTHONPATH', 'PYTHONEXTRAPATH'))
         env['PYTHONPATH'] = os.pathsep.join(p for p in pythonpath if p)
 
         args = [sys.executable, '-m', 'pip']
@@ -1870,9 +1866,9 @@ def call_pip_command(command, operand, options, verbosity=-10):
         log_level = logger.getEffectiveLevel()
         pip_level = log_level - verbosity
         if pip_level >= logging.WARNING:
-        args.append('-' + 'q' * (1 + (pip_level >= logging.ERROR))) # -q or -qq
+            args.append('-' + 'q' * (1 + (pip_level >= logging.ERROR)))
         elif pip_level < logging.INFO:
-        args.append('-' + 'v' * (1 + (pip_level < logging.DEBUG))) # -v or -vv
+            args.append('-' + 'v' * (1 + (pip_level < logging.DEBUG)))
         # Note: more recent pip accepts even -vvv and -qqq.
 
         if not options._allow_picked_versions:
@@ -1887,7 +1883,12 @@ def call_pip_command(command, operand, options, verbosity=-10):
             # build dependencies specified in setup_requires option of
             # legacy setup.py by providing a crafted .pydistutils.cfg.
             # This is used in complement to --no-build-isolation.
-        env['HOME'] = pip_pydistutils_home
+            pip_home = tempfile.mkdtemp('pip-pydistutils-home')
+            cleanup.append(lambda: zc.buildout.rmtree.rmtree(pip_home))
+            with open(os.path.join(pip_home, '.pydistutils.cfg'), 'w') as f:
+                f.write("[easy_install]\n"
+                        "index_url = file:///dev/null")
+            env['HOME'] = pip_home
 
         if PIP_HAS_PYTHON_VERSION_WARNING_OPTION:
             # Let pip display Python warnings only on first run.
@@ -1903,10 +1904,14 @@ def call_pip_command(command, operand, options, verbosity=-10):
             logger.debug('Running pip %s', ' '.join(command[0:1] + operand))
         if log_level < 0:
             # Log this only when buildout log level is even lower
-        logger.debug('%s\nPYTHONPATH=%s\n', ' '.join(args), env['PYTHONPATH'])
+            logger.debug(
+                '%s\nPYTHONPATH=%s\n', ' '.join(args), env['PYTHONPATH'])
 
         sys.stdout.flush() # We want any pending output first
         subprocess.check_call(args, env=env)
+    finally:
+        for f in cleanup:
+            f()
 
 
 def call_pip_editable(path, dest, options, verbosity=-10):