win32: properly restore BB_ env vars

Some BB_ shell variables get special treatment:  they're updated in
the environment immediately on any change.  One case was missed:
if such a variable was unset or not exported and was overridden by
a local variable it wasn't unset in the environment when the local
variable went out of scope.

Add the code required to do this.

Adds 48-64 bytes.

(GitHub issue #423)

1 files changed, 11 insertions, 1 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 9ef8f7742..b894a2314 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -10948,6 +10948,9 @@ poplocalvars(int keep)
         struct localvar_list *ll;
         struct localvar *lvp, *next;
         struct var *vp;
+#if ENABLE_PLATFORM_MINGW32
+        int var_type;
+#endif
 
         INT_OFF;
         ll = localvar_stack;
@@ -10991,8 +10994,15 @@ poplocalvars(int keep)
                         vp->flags = lvp->flags;
                         vp->var_text = lvp->text;
 #if ENABLE_PLATFORM_MINGW32
-                        if (is_bb_var(lvp->text) == BB_VAR_ASSIGN)
+                        var_type = is_bb_var(lvp->text);
+                        if (var_type == BB_VAR_ASSIGN && (lvp->flags & VEXPORT))
                                 putenv(lvp->text);
+                        else if (var_type) {
+                                char *var = xstrdup(lvp->text);
+                                *strchrnul(var, '=') = '\0';
+                                unsetenv(var);
+                                free(var);
+                        }
 #endif
                 }
                 free(lvp);