libdpkg: Properly restore errno in push_cleanup

The code was saving errno for latter use, but stomping on the saved
value by assigning again errno to it. Invert the assignment so that
we restore errno instead of losing it.

lib/dpkg/ehandle.c

@@ -200,7 +200,7 @@ void push_cleanup(void (*call1)(int argc, void **argv), int mask1,
                   unsigned int nargs, ...) {
   struct cleanupentry *cep;
   void **argv;
-  int e;
+  int e = 0;
   va_list args;
 
   onerr_abort++;
@@ -222,7 +222,10 @@ void push_cleanup(void (*call1)(int argc, void **argv), int mask1,
   va_end(args);
   cep->next= econtext->cleanups;
   econtext->cleanups= cep;
-  if (cep == &emergency.ce) { e= errno; ohshite(_("out of memory for new cleanup entry")); }
+  if (cep == &emergency.ce) {
+    errno = e;
+    ohshite(_("out of memory for new cleanup entry"));
+  }
 
   onerr_abort--;
 }