Port import fixes from 2.7.

diff --cc Lib/importlib/test/source/test_file_loader.py
Simple merge

diff --cc Lib/test/test_import.py
Simple merge

diff --cc Python/import.c
index 487347ccfbd96905c4876b79e1c9feeb0909faff,beda7f97d274b2f426cf19d3d0e7921ea352c173..d5b89d59668f562d17d39ce41a4e026f3f965041
--- 1/Python/import.c
--- 2/Python/import.c
+++ b/Python/import.c
@@@ -1338,59 -1215,25 +1338,59 @@@ write_compiled_module(PyCodeObject *co
          return;
      }
      PyMarshal_WriteLongToFile(pyc_magic, fp, Py_MARSHAL_VERSION);
 -    /* First write a 0 for mtime */
 +    /* First write a 0 for mtime and size */
 +    PyMarshal_WriteLongToFile(0L, fp, Py_MARSHAL_VERSION);
      PyMarshal_WriteLongToFile(0L, fp, Py_MARSHAL_VERSION);
      PyMarshal_WriteObjectToFile((PyObject *)co, fp, Py_MARSHAL_VERSION);
-     /* Now write the true mtime and size */
 +    fflush(fp);
-     assert(mtime < LONG_MAX);
++    /* Now write the true mtime and size (as 32-bit fields) */
 +    fseek(fp, 4L, 0);
++    assert(mtime <= 0xFFFFFFFF);
 +    PyMarshal_WriteLongToFile((long)mtime, fp, Py_MARSHAL_VERSION);
 +    PyMarshal_WriteLongToFile(size, fp, Py_MARSHAL_VERSION);
      if (fflush(fp) != 0 || ferror(fp)) {
          if (Py_VerboseFlag)
 -            PySys_WriteStderr("# can't write %s\n", cpathname);
 +            PySys_FormatStderr("# can't write %R\n", cpathname);
          /* Don't keep partial file */
          fclose(fp);
 -        (void) unlink(cpathname);
 +#ifdef MS_WINDOWS
 +        (void)DeleteFileW(wpathname_tmp);
 +        Py_DECREF(cpathname_tmp);
 +#else
 +        (void) unlink(PyBytes_AS_STRING(cpathbytes_tmp));
 +        Py_DECREF(cpathbytes);
 +        Py_DECREF(cpathbytes_tmp);
 +#endif
          return;
      }
 -    /* Now write the true mtime (as a 32-bit field) */
 -    fseek(fp, 4L, 0);
 -    assert(mtime <= 0xFFFFFFFF);
 -    PyMarshal_WriteLongToFile((long)mtime, fp, Py_MARSHAL_VERSION);
 -    fflush(fp);
      fclose(fp);
 +    /* Do a (hopefully) atomic rename */
 +#ifdef MS_WINDOWS
 +    if (!MoveFileExW(wpathname_tmp, wpathname, MOVEFILE_REPLACE_EXISTING)) {
 +        if (Py_VerboseFlag)
 +            PySys_FormatStderr("# can't write %R\n", cpathname);
 +        /* Don't keep tmp file */
 +        (void) DeleteFileW(wpathname_tmp);
 +        Py_DECREF(cpathname_tmp);
 +        return;
 +    }
 +    Py_DECREF(cpathname_tmp);
 +#else
 +    if (rename(PyBytes_AS_STRING(cpathbytes_tmp),
 +               PyBytes_AS_STRING(cpathbytes))) {
 +        if (Py_VerboseFlag)
 +            PySys_FormatStderr("# can't write %R\n", cpathname);
 +        /* Don't keep tmp file */
 +        unlink(PyBytes_AS_STRING(cpathbytes_tmp));
 +        Py_DECREF(cpathbytes);
 +        Py_DECREF(cpathbytes_tmp);
 +        return;
 +    }
 +    Py_DECREF(cpathbytes);
 +    Py_DECREF(cpathbytes_tmp);
 +#endif
      if (Py_VerboseFlag)
 -        PySys_WriteStderr("# wrote %s\n", cpathname);
 +        PySys_FormatStderr("# wrote %R\n", cpathname);
  }
  
  static void
@@@ -1472,28 -1298,22 +1472,28 @@@ load_source_module(PyObject *name, PyOb
  
      if (fstat(fileno(fp), &st) != 0) {
          PyErr_Format(PyExc_RuntimeError,
 -                     "unable to get file status from '%s'",
 +                     "unable to get file status from %R",
                       pathname);
 -        return NULL;
 +        goto error;
      }
- #if SIZEOF_TIME_T > 4
-     /* Python's .pyc timestamp handling presumes that the timestamp fits
-        in 4 bytes. Since the code only does an equality comparison,
-        ordering is not important and we can safely ignore the higher bits
-        (collisions are extremely unlikely).
-      */
-     st.st_mtime &= 0xFFFFFFFF;
- #endif
+     if (sizeof st.st_mtime > 4) {
+         /* Python's .pyc timestamp handling presumes that the timestamp fits
+            in 4 bytes. Since the code only does an equality comparison,
+            ordering is not important and we can safely ignore the higher bits
+            (collisions are extremely unlikely).
+          */
+         st.st_mtime &= 0xFFFFFFFF;
+     }
 -    cpathname = make_compiled_pathname(
 -        pathname, buf, (size_t)MAXPATHLEN + 1, !Py_OptimizeFlag);
 -    if (cpathname != NULL &&
 -        (fpc = check_compiled_module(pathname, st.st_mtime, cpathname))) {
 +    if (PyUnicode_READY(pathname) < 0)
 +        return NULL;
 +    cpathname = make_compiled_pathname(pathname, !Py_OptimizeFlag);
 +
 +    if (cpathname != NULL)
 +        fpc = check_compiled_module(pathname, &st, cpathname);
 +    else
 +        fpc = NULL;
 +
 +    if (fpc) {
          co = read_compiled_module(cpathname, fpc);
          fclose(fpc);
          if (co == NULL)