Fix editable installation from relative paths on Windows

When running `pipenv install -e .\..\mypackage` the pip requirement
line `-e .\..\mypackage` is written to a temporary requirements file
which is passed to pip to install the package. pip fails to install
the package from the requirements file as it incorrectly interprets
the relative path, treating the slashes as escapes. To work around
this issue replace all back slashes (windows directory separators)
with forward slashes (POSIX directory separators) in pip requirements
for editable package installs.

Author: stewartmiles

pipenv/project.py

@@ -15,7 +15,7 @@
 from urllib.parse import unquote, urljoin
 
 from pipenv.utils.constants import VCS_LIST
-from pipenv.utils.dependencies import extract_vcs_url
+from pipenv.utils.dependencies import extract_vcs_url, normalize_editable_path_for_pip
 from pipenv.vendor.tomlkit.items import SingleKey, Table
 
 try:
@@ -1187,9 +1187,14 @@ def generate_package_pipfile_entry(
         if extras:
             entry["extras"] = list(extras)
         if path_specifier:
-            entry["file"] = unquote(str(path_specifier))
-            if pip_line.startswith("-e"):
-                entry["editable"] = True
+            editable = pip_line.startswith("-e")
+            entry["file"] = unquote(
+                normalize_editable_path_for_pip(path_specifier)
+                if editable
+                else str(path_specifier)
+            )
+            if editable:
+                entry["editable"] = editable
         elif vcs_specifier:
             for vcs in VCS_LIST:
                 if vcs in package.link.scheme:

pipenv/routines/install.py

@@ -13,6 +13,7 @@
     expansive_install_req_from_line,
     get_lockfile_section_using_pipfile_category,
     install_req_from_pipfile,
+    normalize_editable_path_for_pip,
 )
 from pipenv.utils.indexes import get_source_list
 from pipenv.utils.internet import download_file, is_valid_url
@@ -44,7 +45,9 @@ def handle_new_packages(
     new_packages = []
     if packages or editable_packages:
 
-        pkg_list = packages + [f"-e {pkg}" for pkg in editable_packages]
+        pkg_list = packages + [
+            f"-e {normalize_editable_path_for_pip(pkg)}" for pkg in editable_packages
+        ]
 
         for pkg_line in pkg_list:
             console.print(f"Installing {pkg_line}...", style="bold green")
@@ -262,7 +265,11 @@ def do_install(
     )
     warnings.filterwarnings("ignore", category=ResourceWarning)
     packages = packages if packages else []
-    editable_packages = editable_packages if editable_packages else []
+    editable_packages = (
+        [normalize_editable_path_for_pip(p) for p in editable_packages]
+        if editable_packages
+        else []
+    )
     package_args = [p for p in packages if p] + [p for p in editable_packages if p]
     new_packages = []
     if dev and not pipfile_categories:

pipenv/utils/dependencies.py

@@ -1068,6 +1068,13 @@ def expansive_install_req_from_line(
     return install_req, name
 
 
+def normalize_editable_path_for_pip(path_str):
+    """Normalize an editable package path for pip."""
+    # Windows paths need to be converted to POSIX paths otherwise path
+    # separators (back slashes) are interpreted as escape characters.
+    return path_str.replace(os.path.sep, "/")
+
+
 def file_path_from_pipfile(path_str, pipfile_entry):
     """Creates an installable file path from a pipfile entry.
     Handles local and remote paths, files and directories;
@@ -1082,7 +1089,7 @@ def file_path_from_pipfile(path_str, pipfile_entry):
     if pipfile_entry.get("extras"):
         req_str = f"{req_str}[{','.join(pipfile_entry['extras'])}]"
     if pipfile_entry.get("editable", False):
-        req_str = f"-e {req_str}"
+        req_str = f"-e {normalize_editable_path_for_pip(req_str)}"
 
     return req_str