Merge with stable

run-tests: add --shell command line flag This makes it easy to test with, say, both /bin/bash and /bin/dash instead of changing the system-wide /bin/sh. [ original upstream message ]

run-tests: use type of default to convert environment variable Before, defaults could only be integers, they can now also be strings, floats and what have you. [ original upstream message ]

run-tests.py: correctly handle list options with parallel tasks [ original upstream message ]

prevent transient leaks of file handle by using new helper functions These leaks may occur in environments that don't employ a reference counting GC, i.e. PyPy. This implies: - changing opener(...).read() calls to opener.read(...) - changing opener(...).write() calls to opener.write(...) - changing open(...).read(...) to util.readfile(...) - changing open(...).write(...) to util.writefile(...) [ original upstream description ]

localrepo: reuse parent manifest in commitctx if no files have changed This speeds up the in-memory version of debugbuilddag that I'm working on considerably for the case where we want to build just a 00changelog.i (for discovery tests, for instance). There are a couple of test changes because node ids in tests have changed. The changes to the patch names in test-mq-qdelete.t were required because they could collide with nodeid abbreviations and newly actually do (patch "c" collides with id "cafe..." for patch "b"). [ original upstream description ]

Merge with stable