In 3.3 iterparse accepts a tuple in events (the C accelerator enforces this).
This limitation was lifted in Python 3.4

It is causing trouble like e.g. hanging processes.

The underlying C libraries provide no mechanism for serializing compressor and
decompressor objects, so actually pickling these classes is impractical.
Previously, these objects would be pickled without error, but attempting to use
a deserialized instance would segfault the interpreter.

screen refresh problem.

pseudo-random number generator on fork().

100 headers are read.  Adapted from patch by Jyrki Pulliainen.

prevent readline() calls from consuming too much memory.  Patch by Jyrki
Pulliainen.

prevent readline() calls from consuming too much memory.  Patch by Jyrki
Pulliainen.

for security reasons.  It now doesn't match multiple wildcards nor wildcards
inside IDN fragments.