[3.13] gh-122765: make prompt in activate.csh robust against unbalanced quotes and newlines (GH-123751) (GH-124185)

gh-122765: make prompt in activate.csh robust against unbalanced quotes and newlines (GH-123751)
(cherry picked from commit a15a584bf3f94ea11ab9363548c8872251364000)

Co-authored-by: Jacek <jacek.duszenko@gmail.com>
Co-authored-by: Brett Cannon <brett@python.org>
diff --git a/Lib/venv/scripts/posix/activate.csh b/Lib/venv/scripts/posix/activate.csh
index c707f19..b5db4a0 100644
--- a/Lib/venv/scripts/posix/activate.csh
+++ b/Lib/venv/scripts/posix/activate.csh
@@ -19,7 +19,7 @@
 set _OLD_VIRTUAL_PROMPT="$prompt"
 
 if (! "$?VIRTUAL_ENV_DISABLE_PROMPT") then
-    set prompt = "(__VENV_PROMPT__) $prompt"
+    set prompt = "(__VENV_PROMPT__) $prompt:q"
 endif
 
 alias pydoc python -m pydoc
diff --git a/Misc/NEWS.d/next/Library/2024-09-06-00-00-43.gh-issue-122765.tx4hsr.rst b/Misc/NEWS.d/next/Library/2024-09-06-00-00-43.gh-issue-122765.tx4hsr.rst
new file mode 100644
index 0000000..8a1bc4b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-09-06-00-00-43.gh-issue-122765.tx4hsr.rst
@@ -0,0 +1 @@
+Fix unbalanced quote errors occurring when activate.csh in :mod:`venv` was sourced with a custom prompt containing unpaired quotes or newlines.