Redis test: when assertion fails print not just the expression but al…

…so expanded values in the error message.

tests/support/test.tcl

@@ -5,7 +5,7 @@ set ::tests_failed {}
 
 proc assert {condition} {
     if {![uplevel 1 expr $condition]} {
-        error "assertion:Expected condition '$condition' to be true"
+        error "assertion:Expected condition '$condition' to be true ([uplevel 1 [list subst -nocommands $condition]])"
     }
 }