msvcrt: Fix freopen() on FILE with invalid underlying fd.

dlls/msvcrt/file.c

@@ -4588,9 +4588,7 @@ FILE* CDECL _wfreopen(const wchar_t *path, const wchar_t *mode, FILE* file)
     TRACE(":path (%s) mode (%s) file (%p) fd (%d)\n", debugstr_w(path), debugstr_w(mode), file, file ? file->_file : -1);
 
     LOCK_FILES();
-    if (!file || ((fd = file->_file) < 0))
-        file = NULL;
-    else
+    if (file)
     {
         fclose(file);
         if (msvcrt_get_flags(mode, &open_flags, &stream_flags) == -1)

dlls/msvcrt/tests/file.c

@@ -1236,6 +1236,25 @@ static void test_freopen( void )
     ok(ret == EOF, "fclose(file) succeeded\n");
     ok(errno == 0xdeadbeef, "errno is %d\n", errno);
 
+    file = fopen(filename1, "rb");
+    ok(file != NULL, "couldn't open %s\n", filename1);
+    close(file->_file);
+    file->_file = -1;
+
+    new = freopen(filename2, "rb", file);
+    ok(new == file, "freopen() didn't return same FILE*\n");
+
+    fd = fileno(file);
+    ok(fd > 0, "fileno() returned %d\n", fd);
+
+    ch = '#';
+    ret = fread(&ch, 1, 1, file);
+    ok(ret == 1, "fread() returned %d\n", ret);
+    ok(ch == '2', "Unexpected char\n");
+
+    ret = fclose(file);
+    ok(ret == 0, "fclose(file) returned %d\n", ret);
+
     unlink(filename1);
     unlink(filename2);
 }