Looking at the history of PyTasklet_New I found the changes 20dad21ded9c (2.7-slp) and dae0e80f141d (3.2-slp), which remove - probably by accident - a if (type == NULL) type = &PyTasklet_Type;. The documentation needs some love too: what does "via capture()" mean?
Proposed Solution
I'll re-add the check for NULL and update the documentation.
Activity
Issue #129: fix calling PyTasklet_New( NULL, ...)
merge 3.3-slp (Stackless #129, PyTasklet_New( NULL, ...))
merge 3.4-slp (Stackless #129, PyTasklet_New( NULL, ...))
merge 3.5-slp (Stackless #129, PyTasklet_New( NULL, ...))
bpo-29643: Fix check for --enable-optimizations (GH-129)