Use `info nameofexectuable` to find current executable

tests/integration/replication-4.tcl

 proc start_bg_complex_data {host port db ops} {
-    exec tclsh8.5 tests/helpers/bg_complex_data.tcl $host $port $db $ops &
+    set tclsh [info nameofexecutable]
+    exec $tclsh tests/helpers/bg_complex_data.tcl $host $port $db $ops &
 }
 
 proc stop_bg_complex_data {handle} {

tests/integration/replication.tcl

@@ -78,7 +78,8 @@ start_server {tags {"repl"}} {
 }
 
 proc start_write_load {host port seconds} {
-    exec tclsh8.5 tests/helpers/gen_write_load.tcl $host $port $seconds &
+    set tclsh [info nameofexecutable]
+    exec $tclsh tests/helpers/gen_write_load.tcl $host $port $seconds &
 }
 
 proc stop_write_load {handle} {

tests/test_helper.tcl

@@ -178,6 +178,7 @@ proc find_available_port start {
 
 proc test_server_main {} {
     cleanup
+    set tclsh [info nameofexecutable]
     # Open a listening socket, trying different ports in order to find a
     # non busy one.
     set port [find_available_port 11111]
@@ -191,7 +192,7 @@ proc test_server_main {} {
     set start_port [expr {$::port+100}]
     for {set j 0} {$j < $::numclients} {incr j} {
         set start_port [find_available_port $start_port]
-        set p [exec tclsh8.5 [info script] {*}$::argv \
+        set p [exec $tclsh [info script] {*}$::argv \
             --client $port --port $start_port &]
         lappend ::clients_pids $p
         incr start_port 10