Preserve original letter-casing for displaying

Simplify input path as a relative path to current working directory,
while preserving the original letter-casing at best effort.

Author: wdhongtw

news/6823.bugfix.rst

@@ -0,0 +1 @@
+Better preserve original casing when a path is displayed.

src/pip/_internal/utils/misc.py

@@ -190,10 +190,10 @@ def rmtree_errorhandler(
 def display_path(path: str) -> str:
     """Gives the display value for a given path, making it relative to cwd
     if possible."""
-    path = os.path.normcase(os.path.abspath(path))
-    if path.startswith(os.getcwd() + os.path.sep):
-        path = "." + path[len(os.getcwd()) :]
-    return path
+    rel = os.path.relpath(path)
+    if rel[:2] == "..":
+        return path
+    return os.path.join(".", rel)
 
 
 def backup_dir(dir: str, ext: str = ".bak") -> str: