Test hygiene. This was creating one more thread than it destroyed.

In a -singleproc 1 test run, this caused tests in later test files to fail
because the stray thread causes test results to be different.

1 files changed, 5 insertions, 2 deletions

diff --git a/tests/http.test b/tests/http.test
index 6826448..eb2bf29 100644
--- a/tests/http.test
+++ b/tests/http.test
@@ -47,6 +47,7 @@ if {![file exists $httpdFile]} {
 catch {package require Thread 2.7-}
 if {[catch {package present Thread}] == 0 && [file exists $httpdFile]} {
     set httpthread [thread::create -preserved]
+    lappend threadStack [list thread::release $httpthread]
     thread::send $httpthread [list source $httpdFile]
     thread::send $httpthread [list set bindata $bindata]
     thread::send $httpthread {httpd_init 0; set port} port
@@ -64,6 +65,7 @@ if {[catch {package present Thread}] == 0 && [file exists $httpdFile]} {
 	catch {unset port}
 	return
     }
+    set threadStack {}
 }
 
 if {![info exists ThreadLevel]} {
@@ -78,6 +80,7 @@ if {![info exists ThreadLevel]} {
     foreach ThreadLevel $ValueRange {
         source [info script]
     }
+    try [lpop threadStack]
     catch {unset ThreadLevel}
     catch {unset ValueRange}
     return
@@ -1168,8 +1171,8 @@ catch {unset url}
 catch {unset badurl}
 catch {unset port}
 catch {unset data}
-if {[info exists httpthread]} {
-    thread::release $httpthread
+if {[llength $threadStack]} {
+    try [lpop threadStack]
 } else {
     close $listen
 }