# 
# 
# patch "tester.cc"
#  from [92f084120ecb09cf0c92c3f291070cfe250a88b8]
#    to [dd220bcf13b0837562660dbcbd1eadc5f85e6784]
# 
# patch "tester.lua"
#  from [5fbd70278ff8878b3d5ee65b0650449f90356132]
#    to [8ec06c74bad74bfd0fb2000f39cc2c88d18c5467]
# 
============================================================
--- tester.cc	92f084120ecb09cf0c92c3f291070cfe250a88b8
+++ tester.cc	dd220bcf13b0837562660dbcbd1eadc5f85e6784
@@ -413,15 +413,30 @@ LUAEXT(set_env, )
 {
   char const * var = luaL_checkstring(L, -2);
   char const * val = luaL_checkstring(L, -1);
-  char const * old = getenv(var);
-  if (old)
-    orig_env_vars.insert(make_pair(string(var), string(old)));
-  else
-    orig_env_vars.insert(make_pair(string(var), ""));
+  if (orig_env_vars.find(string(var)) == orig_env_vars.end()) {
+    char const * old = getenv(var);
+    if (old)
+      orig_env_vars.insert(make_pair(string(var), string(old)));
+    else
+      orig_env_vars.insert(make_pair(string(var), ""));
+  }
   setenv(var, val);
   return 0;
 }
 
+LUAEXT(unset_env, )
+{
+  char const * var = luaL_checkstring(L, -2);
+  if (orig_env_vars.find(string(var)) == orig_env_vars.end()) {
+    char const * old = getenv(var);
+    if (old)
+      orig_env_vars.insert(make_pair(string(var), string(old)));
+    else
+      orig_env_vars.insert(make_pair(string(var), ""));
+  }
+  unsetenv(var);
+}
+
 LUAEXT(timed_wait, )
 {
   pid_t pid = static_cast<pid_t>(luaL_checknumber(L, -2));
============================================================
--- tester.lua	5fbd70278ff8878b3d5ee65b0650449f90356132
+++ tester.lua	8ec06c74bad74bfd0fb2000f39cc2c88d18c5467
@@ -818,6 +818,7 @@ function run_tests(args)
   local of_interest = {}
 
   local function runtest(i, tname)
+    save_env()
     local env = {}
     local genv = getfenv(0)
     for x,y in pairs(genv) do
@@ -888,7 +889,6 @@ function run_tests(args)
         end
       end
       test.errline = errline
-      restore_env()
       posix_umask(oldmask)
     end
     
@@ -947,9 +947,9 @@ function run_tests(args)
       end
     end
     counts.total = counts.total + 1
+    restore_env()
   end
 
-  save_env()
   if run_all then
     for i,t in pairs(tests) do
       if list_only then