mq: introduce qpop --check qpop --check let you qpop with uncommitted files if they do not intersect with files touched by the popped patches.

pager: check if signal.SIGPIPE exists We have to check for signal.SIGPIPE before we attempt to set it.

diffhelpers: harden testhunk

patch: fix segfault against unified diffs which start line is zero Since 2b1ec74c961f, if a chunk starts with "@@ -0,1", oldstart turns into a negative value. Because diffhelpers.testhunk() doesn't expect negative bstart, it bypasses "alen > blen - bstart" condition and segfaults at "PyList_GET_ITEM(b, i + bstart)".

bugzilla: fix transport initialization on python 2.4

bisect: set HG_NODE when runing a command When running a command, set the environment variable HG_NODE to tell the command which changeset is being visited.