[3.13] pythongh-128066: Properly handle history file writes for RO fs on PyREPL (pythongh-134380) (pythongh-134386)

(cherry picked from commit c91ad5d)

Co-authored-by: Chris Patti <[email protected]>
Co-authored-by: Łukasz Langa <[email protected]>

Author: ambv

Lib/site.py

@@ -75,6 +75,7 @@
 import _sitebuiltins
 import io
 import stat
+import errno
 
 # Prefixes for site-packages; add additional prefixes like /usr/local here
 PREFIXES = [sys.prefix, sys.exec_prefix]
@@ -576,6 +577,11 @@ def write_history():
                 # home directory does not exist or is not writable
                 # https://bugs.python.org/issue19891
                 pass
+            except OSError:
+                if errno.EROFS:
+                    pass  # gh-128066: read-only file system
+                else:
+                    raise
 
         atexit.register(write_history)
 

Misc/NEWS.d/next/Core_and_Builtins/2025-05-20-14-41-50.gh-issue-128066.qzzGfv.rst

@@ -0,0 +1,3 @@
+Fixes an edge case where PyREPL improperly threw an error when Python is
+invoked on a read only filesystem while trying to write history file
+entries.