Tweak at the suggestion of Ezio Melotti for exception messages when

EOF is hit while trying to read the header of a bytecode file.

Lib/importlib/_bootstrap.py

@@ -668,11 +668,11 @@ def _validate_bytecode_header(data, source_stats=None, name=None, path=None):
         _verbose_message(message)
         raise ImportError(message, **exc_details)
     elif len(raw_timestamp) != 4:
-        message = 'incomplete timestamp in {!r}'.format(name)
+        message = 'reached EOF while reading magic number in {!r}'.format(name)
         _verbose_message(message)
         raise EOFError(message)
     elif len(raw_size) != 4:
-        message = 'incomplete size in {!r}'.format(name)
+        message = 'reached EOF while reading size in {!r}'.format(name)
         _verbose_message(message)
         raise EOFError(message)
     if source_stats is not None:

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.4.0 Alpha 1?
 Core and Builtins
 -----------------
 
+- Tweak the exception message when the magic number or size value in a bytecode
+  file is truncated.
+
 - Issue #18065: Don't set __path__ to the package name for frozen packages.
 
 - Issue #18088: When reloading a module, unconditionally reset all relevant