[Python-checkins] gh-93858: Prevent error when activating venv in nested fish instances (GH-93931)

[vsajip]

https://github.com/python/cpython/commit/117217245390ed3e6fe166180f052e022d296921
commit: 117217245390ed3e6fe166180f052e022d296921
branch: main
author: Thomas B. Brunner <thomasbbrunner at gmail.com>
committer: vsajip <vinay_sajip at yahoo.co.uk>
date: 2022-06-27T16:26:02+01:00
summary:

gh-93858: Prevent error when activating venv in nested fish instances (GH-93931)

files:
A Misc/NEWS.d/next/Library/2022-06-17-12-02-30.gh-issue-93858.R49ARc.rst
M Lib/venv/scripts/posix/activate.fish

diff --git a/Lib/venv/scripts/posix/activate.fish b/Lib/venv/scripts/posix/activate.fish
index e40a1d714894f..9aa4446005f4d 100644
--- a/Lib/venv/scripts/posix/activate.fish
+++ b/Lib/venv/scripts/posix/activate.fish
@@ -13,10 +13,13 @@ function deactivate  -d "Exit virtual environment and return to normal shell env
     end
 
     if test -n "$_OLD_FISH_PROMPT_OVERRIDE"
-        functions -e fish_prompt
         set -e _OLD_FISH_PROMPT_OVERRIDE
-        functions -c _old_fish_prompt fish_prompt
-        functions -e _old_fish_prompt
+        # prevents error when using nested fish instances (Issue #93858)
+        if functions -q _old_fish_prompt
+            functions -e fish_prompt
+            functions -c _old_fish_prompt fish_prompt
+            functions -e _old_fish_prompt
+        end
     end
 
     set -e VIRTUAL_ENV
diff --git a/Misc/NEWS.d/next/Library/2022-06-17-12-02-30.gh-issue-93858.R49ARc.rst b/Misc/NEWS.d/next/Library/2022-06-17-12-02-30.gh-issue-93858.R49ARc.rst
new file mode 100644
index 0000000000000..508ba626bab41
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-06-17-12-02-30.gh-issue-93858.R49ARc.rst
@@ -0,0 +1 @@
+Prevent error when activating venv in nested fish instances.