diff --git a/pipenv/project.py b/pipenv/project.py
index f7e661c161..15cc231ce0 100644
--- a/pipenv/project.py
+++ b/pipenv/project.py
@@ -333,7 +333,8 @@ def get_hashes_from_remote_index_urls(self, ireq, source):
                 )
             return None
 
-    def get_file_hash(self, session, link):
+    @staticmethod
+    def get_file_hash(session, link):
         h = hashlib.new(FAVORITE_HASH)
         err.print(f"Downloading file {link.filename} to obtain hash...")
         with open_file(link.url, session) as fp:
@@ -1126,7 +1127,7 @@ def generate_package_pipfile_entry(self, package, pip_line, category=None):
         if extras:
             entry["extras"] = list(extras)
         if path_specifier:
-            entry["file"] = unquote(path_specifier)
+            entry["file"] = unquote(str(path_specifier))
         elif vcs_specifier:
             for vcs in VCS_LIST:
                 if vcs in package.link.scheme:
diff --git a/pipenv/utils/dependencies.py b/pipenv/utils/dependencies.py
index dd2207275a..cf311d25c1 100644
--- a/pipenv/utils/dependencies.py
+++ b/pipenv/utils/dependencies.py
@@ -11,7 +11,7 @@
 from pathlib import Path
 from tempfile import NamedTemporaryFile, TemporaryDirectory
 from typing import Any, AnyStr, Dict, List, Mapping, Optional, Sequence, Union
-from urllib.parse import urljoin, urlparse, urlsplit, urlunsplit
+from urllib.parse import urlparse, urlsplit, urlunsplit
 
 from pipenv.patched.pip._internal.models.link import Link
 from pipenv.patched.pip._internal.network.download import Downloader
@@ -639,15 +639,12 @@ def find_package_name_from_directory(directory):
 def determine_path_specifier(package: InstallRequirement):
     if package.link:
         if package.link.scheme in ["http", "https"]:
-            path_specifier = package.link.url_without_fragment
-            return path_specifier
+            return package.link.url_without_fragment
         if package.link.scheme == "file":
             try:
-                path_specifier = os.path.relpath(package.link.file_path)
+                return Path(package.link.file_path).relative_to(Path.cwd()).as_posix()
             except ValueError:
-                # If os.path.relpath() fails, use the absolute path instead
-                path_specifier = os.path.abspath(package.link.file_path)
-            return path_specifier
+                return Path(package.link.file_path).as_posix()
 
 
 def determine_vcs_specifier(package: InstallRequirement):
@@ -900,13 +897,7 @@ def expansive_install_req_from_line(
     if expand_env:
         name = expand_env_variables(name)
 
-    if os.path.isfile(name) or os.path.isdir(name):
-        if not name.startswith("file:"):
-            # Make sure the path is absolute and properly formatted as a file: URL
-            absolute_path = os.path.abspath(name)
-            name = urljoin("file:", absolute_path)
-            name = "file:" + name
-
+    if editable or os.path.isdir(name):
         return install_req_from_editable(name, line_source)
 
     vcs_part = name
@@ -926,9 +917,7 @@ def expansive_install_req_from_line(
                 constraint=constraint,
                 user_supplied=user_supplied,
             )
-    if editable:
-        return install_req_from_editable(name, line_source)
-    if urlparse(name).scheme in ("http", "https", "file"):
+    if urlparse(name).scheme in ("http", "https", "file") or os.path.isfile(name):
         parts = parse_req_from_line(name, line_source)
     else:
         # It's a requirement
@@ -992,9 +981,9 @@ def install_req_from_pipfile(name, pipfile):
         else:
             req_str = f"{name}{extras_str}@ {req_str}"
     elif "path" in _pipfile:
-        req_str = f"{_pipfile['path']}{extras_str}"
+        req_str = str(Path(_pipfile["path"]).as_posix())
     elif "file" in _pipfile:
-        req_str = f"{_pipfile['file']}{extras_str}"
+        req_str = str(Path(_pipfile["file"]).as_posix())
     else:
         # We ensure version contains an operator. Default to equals (==)
         _pipfile["version"] = version = get_version(pipfile)
diff --git a/pipenv/utils/funktools.py b/pipenv/utils/funktools.py
index de5668b0ab..9a056d6681 100644
--- a/pipenv/utils/funktools.py
+++ b/pipenv/utils/funktools.py
@@ -9,7 +9,7 @@
 import time
 import warnings
 from functools import partial
-from itertools import count, islice, tee
+from itertools import count, islice
 from typing import Any, Iterable
 
 DIRECTORY_CLEANUP_TIMEOUT = 1.0
@@ -62,18 +62,13 @@ def unnest(elem: Iterable) -> Any:
     """
 
     if isinstance(elem, Iterable) and not isinstance(elem, str):
-        elem, target = tee(elem, 2)
-    else:
-        target = elem
-    if not target or not _is_iterable(target):
-        yield target
-    else:
-        for el in target:
+        for el in elem:
             if isinstance(el, Iterable) and not isinstance(el, str):
-                el, el_copy = tee(el, 2)
-                yield from unnest(el_copy)
+                yield from unnest(el)
             else:
                 yield el
+    else:
+        yield elem
 
 
 def dedup(iterable: Iterable) -> Iterable:
diff --git a/tests/integration/test_install_uri.py b/tests/integration/test_install_uri.py
index e11ac38d74..01855f5e72 100644
--- a/tests/integration/test_install_uri.py
+++ b/tests/integration/test_install_uri.py
@@ -187,7 +187,7 @@ def test_install_local_vcs_not_in_lockfile(pipenv_instance_pypi):
 def test_get_vcs_refs(pipenv_instance_private_pypi):
     with pipenv_instance_private_pypi() as p:
         c = p.pipenv(
-            "install -e git+https://github.com/benjaminp/six.git@1.9.0"
+            "install -e git+https://github.com/benjaminp/six.git@1.9.0#egg=six"
         )
         assert c.returncode == 0
         assert "six" in p.pipfile["packages"]