ERR: stringify error message from parsers.pyx, closes #29233

pandas/_libs/parsers.pyx

@@ -657,7 +657,7 @@ cdef class TextReader:
 
         if isinstance(source, str):
             encoding = sys.getfilesystemencoding() or "utf-8"
-
+            usource = source
             source = source.encode(encoding)
 
             if self.memory_map:
@@ -677,10 +677,11 @@ cdef class TextReader:
 
             if ptr == NULL:
                 if not os.path.exists(source):
+
                     raise FileNotFoundError(
                         ENOENT,
-                        f'File {source} does not exist',
-                        source)
+                        f'File {usource} does not exist',
+                        usource)
                 raise IOError('Initializing from file failed')
 
             self.parser.source = ptr

pandas/tests/io/parser/test_common.py

@@ -2,7 +2,6 @@
 Tests that work on both the Python and C engines but do not have a
 specific classification into the other test modules.
 """
-
 import codecs
 from collections import OrderedDict
 import csv
@@ -978,15 +977,15 @@ def test_path_local_path(all_parsers):
 def test_nonexistent_path(all_parsers):
     # gh-2428: pls no segfault
     # gh-14086: raise more helpful FileNotFoundError
+    # GH#29233 "File foo" instead of "File b'foo'"
     parser = all_parsers
     path = "{}.csv".format(tm.rands(10))
 
-    msg = "does not exist" if parser.engine == "c" else r"\[Errno 2\]"
+    msg = f"File {path} does not exist" if parser.engine == "c" else r"\[Errno 2\]"
     with pytest.raises(FileNotFoundError, match=msg) as e:
         parser.read_csv(path)
 
         filename = e.value.filename
-        filename = filename.decode() if isinstance(filename, bytes) else filename
 
         assert path == filename