Add test-case which demonstrates the problem. This test-case fails in trunk (but passes in core-8-5-branch, as expected).

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/env.test b/tests/env.test
index 83d99e0..f9df4d6 100644
--- a/tests/env.test
+++ b/tests/env.test
@@ -314,6 +314,19 @@ test env-7.2 {[219226]: links to env elements should not be removed by read} {
     }}
 } ok
 
+test env-7.3 {[9b4702]: testing existence of env(some_thing) should not destroy trace} {
+    apply {{} {
+      catch {unset ::env(test7_3)}
+      proc foo args {
+        set ::env(test7_3) ok
+      }
+      trace add variable ::env(not_yet_existent) write foo
+      info exists ::env(not_yet_existent)
+      set ::env(not_yet_existent) "Now I'm here";
+      info exists ::env(test7_3)
+    }}
+} 1
+
 # Restore the environment variables at the end of the test.
 
 foreach name [array names env] {