debugrevlog: display details about empty revision We now display details about the course of emptiness (empty text or empty delta).

debugrevlog: track empty revlog entries A revlog entry can be "empty" for two reasons: * the stored text is empty * we found another entry with the exact same content Tracking them separately make revlog content clearer.

debugrevlog: document some of the variable used This help to understand the code.

revlog: drop compatibility for `revlog.descendant` (API) As advertised, the method is dropped in 4.8.

context: drop compatibility for `context.descendant` (API) As advertised, the method is dropped in 4.8.

cmdutil: remove _updatecleanmsg() which is no longer used anywhere

cmdutil: fix weird indent in _mergemsg()

cext: fix a warning about differing const qualifiers on Windows The prototype takes a 'void *', but self->offsets is a 'const char **'. mercurial/cext/revlog.c(2011) : warning C4090: 'function' : different 'const' qualifiers

cext: fix most truncation warnings in revlog on Windows There's one more, and I'm not sure why it isn't being tripped on other platforms: mercurial/cext/revlog.c(430) : warning C4244: '=' : conversion from 'Py_ssize_t' to 'char', possible loss of data

cext: fix Windows warning about implicit conversion of 32-bit shift to 64 bit mercurial/cext/revlog.c(1541) : warning C4334: '<<' : result of 32-bit shift implicitly converted to 64 bits (was 64-bit shift int ended?)