Index: openacs-4/packages/acs-lang/tcl/localization-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-lang/tcl/localization-procs.tcl,v
diff -u -r1.29.2.10 -r1.29.2.11
--- openacs-4/packages/acs-lang/tcl/localization-procs.tcl	16 Dec 2019 12:41:54 -0000	1.29.2.10
+++ openacs-4/packages/acs-lang/tcl/localization-procs.tcl	18 May 2020 21:13:20 -0000	1.29.2.11
@@ -373,11 +373,9 @@
     # Keep the results of lc_time_fmt_compile in the per-thread cache
     # (namespaced variable)
     #
-    set key ::acs::lc_time_fmt_compile($fmt,$locale)
-    if {![info exists $key]} {
-        set $key [lc_time_fmt_compile $fmt $locale]
-    }
-    return [subst [set $key]]
+    return [subst [acs::per_thread_cache eval -key acs-lang:lc_time_fmt_compile($fmt,$locale) {
+        lc_time_fmt_compile $fmt $locale
+    }]]
 }
 
 ad_proc -public lc_time_fmt_compile {