Restore argc/argv in EXEC after command is executed

src/multi.c

@@ -110,6 +110,10 @@ void execCommand(redisClient *c) {
         c->argc = c->mstate.commands[j].argc;
         c->argv = c->mstate.commands[j].argv;
         call(c,c->mstate.commands[j].cmd);
+
+        /* Commands may alter argc/argv, restore mstate. */
+        c->mstate.commands[j].argc = c->argc;
+        c->mstate.commands[j].argv = c->argv;
     }
     c->argv = orig_argv;
     c->argc = orig_argc;

tests/unit/other.tcl

@@ -174,6 +174,13 @@ start_server {tags {"other"}} {
         set _ $err
     } {*ERR MULTI*}
 
+    test {MULTI where commands alter argc/argv} {
+        r sadd myset a
+        r multi
+        r spop myset
+        list [r exec] [r exists myset]
+    } {a 0}
+
     test {WATCH inside MULTI is not allowed} {
         set err {}
         r multi