Trace common finder info outside resolver

There's no reason for Resolver to trace this information about our
PackageFinder, we just need a common one-time function to trace useful
information.

src/pip/_internal/cli/req_command.py

@@ -8,6 +8,7 @@ PackageFinder machinery and all its vendored dependencies, etc.
 # The following comment should be removed at some point in the future.
 # mypy: disallow-untyped-defs=False
 
+import logging
 import os
 from functools import partial
 
@@ -41,6 +42,8 @@ if MYPY_CHECK_RUNNING:
     from pip._internal.req.req_tracker import RequirementTracker
     from pip._internal.utils.temp_dir import TempDirectory
 
+logger = logging.getLogger(__name__)
+
 
 class SessionCommandMixin(CommandContextMixIn):
 
@@ -272,6 +275,18 @@ class RequirementCommand(IndexGroupCommand):
                     'You must give at least one requirement to %(name)s '
                     '(see "pip help %(name)s")' % opts)
 
+    @staticmethod
+    def trace_basic_info(finder):
+        # type: (PackageFinder) -> None
+        """
+        Trace basic information about the provided objects.
+        """
+        # Display where finder is looking for packages
+        search_scope = finder.search_scope
+        locations = search_scope.get_formatted_locations()
+        if locations:
+            logger.info(locations)
+
     def _build_package_finder(
         self,
         options,               # type: Values

src/pip/_internal/commands/download.py

@@ -139,6 +139,9 @@ class DownloadCommand(RequirementCommand):
                 options=options,
                 py_version_info=options.python_version,
             )
+
+            self.trace_basic_info(finder)
+
             resolver.resolve(requirement_set)
 
             downloaded = ' '.join([

src/pip/_internal/commands/install.py

@@ -373,6 +373,9 @@ class InstallCommand(RequirementCommand):
                     upgrade_strategy=upgrade_strategy,
                     use_pep517=options.use_pep517,
                 )
+
+                self.trace_basic_info(finder)
+
                 resolver.resolve(requirement_set)
 
                 try:

src/pip/_internal/commands/wheel.py

@@ -185,6 +185,9 @@ class WheelCommand(RequirementCommand):
                     ignore_requires_python=options.ignore_requires_python,
                     use_pep517=options.use_pep517,
                 )
+
+                self.trace_basic_info(finder)
+
                 resolver.resolve(requirement_set)
 
                 # build wheels

src/pip/_internal/legacy_resolve.py

@@ -181,12 +181,6 @@ class Resolver(object):
             any(req.has_hash_options for req in root_reqs)
         )
 
-        # Display where finder is looking for packages
-        search_scope = self.finder.search_scope
-        locations = search_scope.get_formatted_locations()
-        if locations:
-            logger.info(locations)
-
         # Actually prepare the files, and collect any exceptions. Most hash
         # exceptions cannot be checked ahead of time, because
         # req.populate_link() needs to be called before we can make decisions