crecord: stop raising error.Abort if curses is not found (issue5008) On some servers, python curses support is disabled. This patch not only fixes that but provides a fallback on other machines (e.g. Windows) when curses is not found. The previous code was actually flawed logic and relied on wcurses throwing an ImportError which demandimport wouldn't throw. So, this patch also fixes that problem.

cmdutil: use crecordmod.checkcurses Instead of blindly trusting the user's experimental.crecord, we use checkcurses to abstract that logic so that we can handle the case where python was not built with curses.

crecord: ensure that curses is False if not imported This provides no functional change but makes the next two patches easier to review.

crecord: add helper function to determine if we should use curses To fix issue5008 properly, we need a helper function to determine if curses is imported and also if the user has enabled the experimental flag.

crecord: use try/except for import of curses Not only does this improve fragility with 'if os.name == ...' it will help future patches enable the behavior to fallback to use plain record when curses is unavailable (e.g. python compiled without curses support).

histedit: only use pickle if not using the modern save format This avoids a case where PyPy's cPickle module throws a more confusing error than CPython's.

perf: close transaction in perffncachewrite This fixes a bug, and brings CPython behaviour on this test into line with PyPy.

hbisect: use tryreadlines to load state This closes the file handle after reading, which stops PyPy from leaking open file handles and thus failing test-bisect3.t.

eol: make output stable This eliminates a divergence in behaviour between PyPy and Python.

exchange: use absolute_import