shlwapi: SHMapHandle should not set error when NULL is passed as hShared.

dlls/shlwapi/ordinal.c

@@ -97,6 +97,12 @@ HANDLE WINAPI SHMapHandle(HANDLE hShared, DWORD dwSrcProcId, DWORD dwDstProcId,
   TRACE("(%p,%d,%d,%08x,%08x)\n", hShared, dwDstProcId, dwSrcProcId,
         dwAccess, dwOptions);
 
+  if (!hShared)
+  {
+    TRACE("Returning handle NULL\n");
+    return NULL;
+  }
+
   /* Get dest process handle */
   if (dwDstProcId == dwMyProcId)
     hDst = GetCurrentProcess();

dlls/shlwapi/tests/ordinal.c

@@ -556,7 +556,6 @@ static void test_alloc_shared_remote(DWORD procid, HANDLE hmem)
     SetLastError(0xdeadbeef);
     hmem2 = pSHMapHandle(NULL, procid, GetCurrentProcessId(), 0, 0);
     ok(hmem2 == NULL, "expected NULL, got new handle\n");
-todo_wine
     ok(GetLastError() == 0xdeadbeef, "last error should not have changed, got %u\n", GetLastError());
 
     hmem2 = pSHMapHandle(hmem, procid, GetCurrentProcessId(), 0, 0);