This will respect the indexes but it required changing vendored code

pipenv/core.py

@@ -1413,9 +1413,8 @@ def pip_install(
             ignore_hashes = False
     line = None
     # Try installing for each source in project.sources.
-    if requirement.index:
+    if not index and requirement.index:
         index = requirement.index
-        extra_indexes = []
     if index and not extra_indexes:
         extra_indexes = list(project.sources)
         extra_indexes = list(filter(lambda d: d['name'] == requirement.index, extra_indexes))
@@ -1462,7 +1461,8 @@ def pip_install(
         pip_command.extend(["-r", vistir.path.normalize_path(r)])
     elif line:
         pip_command.extend(line)
-    pip_command.extend(prepare_pip_source_args(sources))
+    pip_source_args = prepare_pip_source_args(sources)
+    pip_command.extend(pip_source_args)
     if project.s.is_verbose():
         click.echo(f"$ {cmd_list_to_shell(pip_command)}", err=True)
     cache_dir = Path(project.s.PIPENV_CACHE_DIR)

pipenv/patched/notpip/_internal/index/collector.py

@@ -445,15 +445,18 @@ class LinkCollector:
         self,
         session: PipSession,
         search_scope: SearchScope,
+        index_lookup: dict = None,
     ) -> None:
         self.search_scope = search_scope
         self.session = session
+        self.index_lookup = index_lookup if index_lookup else {}
 
     @classmethod
     def create(
         cls, session: PipSession,
         options: Values,
-        suppress_no_index: bool = False
+        suppress_no_index: bool = False,
+        index_lookup: dict = None,
     ) -> "LinkCollector":
         """
         :param session: The Session to use to make requests.
@@ -472,10 +475,10 @@ class LinkCollector:
         find_links = options.find_links or []
 
         search_scope = SearchScope.create(
-            find_links=find_links, index_urls=index_urls,
+            find_links=find_links, index_urls=index_urls, index_lookup=index_lookup
         )
         link_collector = LinkCollector(
-            session=session, search_scope=search_scope,
+            session=session, search_scope=search_scope, index_lookup=index_lookup
         )
         return link_collector
 

pipenv/patched/notpip/_internal/models/search_scope.py

@@ -20,13 +20,14 @@ class SearchScope:
     Encapsulates the locations that pip is configured to search.
     """
 
-    __slots__ = ["find_links", "index_urls"]
+    __slots__ = ["find_links", "index_urls", "index_lookup"]
 
     @classmethod
     def create(
         cls,
         find_links: List[str],
         index_urls: List[str],
+        index_lookup: dict = None,
     ) -> "SearchScope":
         """
         Create a SearchScope object after normalizing the `find_links`.
@@ -60,15 +61,18 @@ class SearchScope:
         return cls(
             find_links=built_find_links,
             index_urls=index_urls,
+            index_lookup=index_lookup
         )
 
     def __init__(
         self,
         find_links: List[str],
         index_urls: List[str],
+        index_lookup: dict = None,
     ) -> None:
         self.find_links = find_links
         self.index_urls = index_urls
+        self.index_lookup = index_lookup if index_lookup else {}
 
     def get_formatted_locations(self) -> str:
         lines = []
@@ -123,4 +127,7 @@ class SearchScope:
                 loc = loc + '/'
             return loc
 
-        return [mkurl_pypi_url(url) for url in self.index_urls]
+        index_urls = self.index_urls
+        if project_name in self.index_lookup:
+            index_urls = [self.index_lookup[project_name]]
+        return [mkurl_pypi_url(url) for url in index_urls]

pipenv/utils.py

@@ -804,6 +804,14 @@ class Resolver:
                 options=self.pip_options,
                 session=self.session
             )
+        index_mapping = {}
+        for source in self.sources:
+            index_mapping[source['name']] = source['url']
+        alt_index_lookup = {}
+        for req_name, index in self.index_lookup.items():
+            alt_index_lookup[req_name] = index_mapping[index]
+        self._finder._link_collector.index_lookup = alt_index_lookup
+        self._finder._link_collector.search_scope.index_lookup = alt_index_lookup
         return self._finder
 
     @property
@@ -827,7 +835,6 @@ class Resolver:
         from pipenv.vendor.pip_shims import shims
 
         pip_options = self.pip_options
-        print("pip_options", pip_options)
         pip_options.extra_index_urls = []
         if self._parsed_constraints is None:
             self._parsed_constraints = shims.parse_requirements(
@@ -887,9 +894,10 @@ class Resolver:
         from pipenv.vendor.pip_shims.shims import InstallationError
         from pipenv.exceptions import ResolutionFailure
 
+        constraints = self.constraints
         with temp_environ(), self.get_resolver() as resolver:
             try:
-                results = resolver.resolve(self.constraints, check_supported_wheels=False)
+                results = resolver.resolve(constraints, check_supported_wheels=False)
             except InstallationError as e:
                 raise ResolutionFailure(message=str(e))
             else: