(Merge 3.2) Handle correctly _Py_fopen() error: don't replace the exception

Modules/zipimport.c

@@ -742,6 +742,7 @@ read_directory(PyObject *archive)
 
     fp = _Py_fopen(archive, "rb");
     if (fp == NULL) {
+        if (!PyErr_Occurred())
             PyErr_Format(ZipImportError, "can't open Zip file: %R", archive);
         return NULL;
     }
@@ -913,6 +914,7 @@ get_data(PyObject *archive, PyObject *toc_entry)
 
     fp = _Py_fopen(archive, "rb");
     if (!fp) {
+        if (!PyErr_Occurred())
             PyErr_Format(PyExc_IOError,
                "zipimport: can not open file %U", archive);
         return NULL;

Python/import.c

@@ -3760,26 +3760,38 @@ get_file(PyObject *pathname, PyObject *fob, char *mode)
         mode = "r" PY_STDIOTEXTMODE;
     if (fob == NULL) {
         fp = _Py_fopen(pathname, mode);
+        if (!fp) {
+            if (!PyErr_Occurred())
+                PyErr_SetFromErrno(PyExc_IOError);
+            return NULL;
+        }
+        return fp;
     }
     else {
         int fd = PyObject_AsFileDescriptor(fob);
         if (fd == -1)
             return NULL;
-        if (!_PyVerify_fd(fd))
-            goto error;
+        if (!_PyVerify_fd(fd)) {
+            PyErr_SetFromErrno(PyExc_IOError);
+            return NULL;
+        }
+
         /* the FILE struct gets a new fd, so that it can be closed
          * independently of the file descriptor given
          */
         fd = dup(fd);
-        if (fd == -1)
-            goto error;
-        fp = fdopen(fd, mode);
+        if (fd == -1) {
+            PyErr_SetFromErrno(PyExc_IOError);
+            return NULL;
         }
-    if (fp)
-        return fp;
-error:
+
+        fp = fdopen(fd, mode);
+        if (!fp) {
             PyErr_SetFromErrno(PyExc_IOError);
             return NULL;
+        }
+        return fp;
+    }
 }
 
 static PyObject *