bpo-25083: Python can sometimes create incorrect .pyc files (GH-8449)

Python 2 never checked for I/O error when reading .py files and
thus could mistake an I/O error for EOF and create incorrect .pyc
files.
This adds an check for this and aborts on an error.

1 files changed, 3 insertions, 0 deletions

diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 5707c9f524..2c9f55fbd1 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1654,6 +1654,9 @@ err_input(perrdetail *err)
         Py_XDECREF(tb);
         break;
     }
+    case E_IO:
+        msg = "I/O error while reading";
+        break;
     case E_LINECONT:
         msg = "unexpected character after line continuation character";
         break;