[Test] Workaround for importlib crazy behavior

- I can't call pip to install in a specified dir and then import
  using importlib. It always fail, even when the module is installed
  and its path is in sys.path. Couldn't find why.

kibot/dep_downloader.py

@@ -235,10 +235,12 @@ def check_pip():
 
 
 def pip_install(pip_command, dest=None, name='.'):
-    cmd = [pip_command, 'install', '-U', '--no-warn-script-location',
-           # This is what -U (--user) means, but Debian's pip installs to /usr/local when used by root
-           '--root', os.path.dirname(site.USER_BASE), '--prefix', os.path.basename(site.USER_BASE),
-           name]
+    cmd = [pip_command, 'install', '-U', '--no-warn-script-location']
+    if name == '.':
+        # Applied only when installing a downloaded tarball
+        # This is what -U (--user) means, but Debian's pip installs to /usr/local when used by root
+        cmd.extend(['--root', os.path.dirname(site.USER_BASE), '--prefix', os.path.basename(site.USER_BASE)])
+    cmd.append(name)
     logger.debug('- Running: {}'.format(cmd))
     try:
         res_run = subprocess.run(cmd, check=True, capture_output=True, cwd=dest)
@@ -708,9 +710,10 @@ def check_tool_python(dep, reload=False):
         return None
     # Check we can use it
     try:
+        importlib.invalidate_caches()
         mod = importlib.import_module(dep.module_name)
         res = check_tool_python_version(mod, dep)
-        if res is not None and reload is not None:
+        if res is not None and reload:
             res = importlib.reload(reload)
         return res
     except ModuleNotFoundError:

tests/test_plot/test_dep_downloader.py

@@ -49,6 +49,8 @@ def try_dependency(ctx, caplog, monkeypatch, docstring, name_dep, downloader_nam
 
 
 def try_dependency_module(ctx, caplog, monkeypatch, docstring, name_dep, downloader_name):
+    # Note: every attempt to install in a chosen dir failed, even when the module was there and in the sys.path the
+    # importlib call miserably failed.
     with monkeypatch.context():
         # Refresh the module with actual dependencies
         mod = importlib.reload(downloader)
@@ -60,7 +62,7 @@ def try_dependency_module(ctx, caplog, monkeypatch, docstring, name_dep, downloa
         cov.start()
         # Python module
         downloader_func = getattr(mod, downloader_name)
-        res = downloader_func(dep, False)
+        res = downloader_func(dep)
         cov.stop()
         cov.save()
         # We should get the following name: