Closes #25671: Merged fix from 3.5.

Lib/venv/scripts/posix/activate.fish

@@ -15,10 +15,7 @@ function deactivate  -d "Exit virtualenv and return to normal shell environment"
     if test -n "$_OLD_FISH_PROMPT_OVERRIDE"
         functions -e fish_prompt
         set -e _OLD_FISH_PROMPT_OVERRIDE
-        . ( begin
-                printf "function fish_prompt\n\t#"
-                functions _old_fish_prompt
-            end | psub )
+        functions -c _old_fish_prompt fish_prompt
         functions -e _old_fish_prompt
     end
 
@@ -47,28 +44,32 @@ if test -z "$VIRTUAL_ENV_DISABLE_PROMPT"
     # fish uses a function instead of an env var to generate the prompt.
 
     # save the current fish_prompt function as the function _old_fish_prompt
-    . ( begin
-            printf "function _old_fish_prompt\n\t#"
-            functions fish_prompt
-        end | psub )
+    functions -c fish_prompt _old_fish_prompt
 
     # with the original prompt function renamed, we can override with our own.
     function fish_prompt
+        # Save the return status of the last command
+        set -l old_status $status
+
         # Prompt override?
         if test -n "__VENV_PROMPT__"            
-            printf "%s%s%s" "__VENV_PROMPT__" (set_color normal) (_old_fish_prompt)
-            return
-        end
+            printf "%s%s" "__VENV_PROMPT__" (set_color normal)
+        else
             # ...Otherwise, prepend env
             set -l _checkbase (basename "$VIRTUAL_ENV")
             if test $_checkbase = "__"
                 # special case for Aspen magic directories
                 # see http://www.zetadev.com/software/aspen/
-            printf "%s[%s]%s %s" (set_color -b blue white) (basename (dirname "$VIRTUAL_ENV")) (set_color normal) (_old_fish_prompt)
+                printf "%s[%s]%s " (set_color -b blue white) (basename (dirname "$VIRTUAL_ENV")) (set_color normal)
             else
-            printf "%s(%s)%s%s" (set_color -b blue white) (basename "$VIRTUAL_ENV") (set_color normal) (_old_fish_prompt)
+                printf "%s(%s)%s" (set_color -b blue white) (basename "$VIRTUAL_ENV") (set_color normal)
             end
         end
 
+        # Restore the return status of the previous command.
+        echo "exit $old_status" | .
+        _old_fish_prompt
+    end
+
     set -gx _OLD_FISH_PROMPT_OVERRIDE "$VIRTUAL_ENV"
 end