The current behaviour is to return the previous one in the series but at the
same time the implementation is buggy because it does not take guarded patches
in account.
Most of the code paths in mq would always pass patch specifications as a
string. Patches can be specified by their index, but one code path passed that
(through pop) to lookup as an integer - all other code paths used a string.
Unfortunately pop and lookup (like many other parts of mq) used the boolean
value of the patch specification to see if it was None, and they would thus
incorrectly handle patch 0 as None.
This patch makes the code comply with the actual internal duck typing of patch
specifications: patch indices must be encoded as strings. The (now) unused code
for partial and thus incorrect handling of indices as integers is removed.
The internal list representation of guards was leaking into the
output. The guards were always printed using repr(guard) and that
style was kept.
When "hg qguard -l" prints several guards for a patch, it does so by
joining the names with " " and that style was used for the error
messages too.
Using terminfo instead of hard-coding ECMA-48 control sequences provides a
greater assurance that the terminal codes are correct for the current
terminal type; not everything supports the ANSI escape codes.
It also allows us to use a wider range of colors when a terminal emulator
supports it (such as 16- or 256-color xterm), and a few more non-color
attributes, such as the ever-popular blink.
