fixes #5076

compiler/options.nim

@@ -227,8 +227,7 @@ proc setDefaultLibpath*() =
       libpath = parentNimLibPath
 
 proc canonicalizePath*(path: string): string =
-  when not FileSystemCaseSensitive: result = path.expandFilename.toLowerAscii
+  result = path.expandFilename
-  else: result = path.expandFilename
 
 proc shortenDir*(dir: string): string =
   ## returns the interesting part of a dir

tests/modules/UpperCased.nim

@@ -0,0 +1,6 @@
+
+# bug #5076
+
+var str*: string
+
+UpperCased.str = "hello"

tests/modules/tuppercased.nim

@@ -0,0 +1,8 @@
+discard """
+  output: "hello"
+"""
+
+import UpperCased
+
+# stress normalization rules:
+echo Upper_Cased.str