test-lfs: drop a hack for ignoring convert devel-warnings This was fixed on stable in 281214150561.

convert: restore the ability to use bzr < 2.6.0 (issue5733) This effectively conditionalizes a234b32b744a. Some Linux distributions (like CentOS 7) use really old versions, and the change referenced was causing exceptions to be thrown. Even though the deprecation warning says 'since 2.5.0', it wasn't marked as such in 2.5.1, but is by 2.6.0. This was tested with 2.4.2 and 2.6.0 with PYTHONWARNINGS=::DeprecationWarning, and both paths were exercized.

py3: use bytes in place of basestring All strings in mercurial must be bytes so we can easily replace basestring with bytes. Differential Revision: https://phab.mercurial-scm.org/D1555

amend: make a copy of "extra" to avoid mutating an input I don't know of any problems this has caused, it just seems less surprising. Differential Revision: https://phab.mercurial-scm.org/D1575

tests: removes bashism from test-unamend.t FreeBSD builders fail because of bashism. Differential Revision: https://phab.mercurial-scm.org/D1578

run-tests: avoid calculating _testdir again Differential Revision: https://phab.mercurial-scm.org/D1574

run-tests: simplify by using dict.pop() with default Differential Revision: https://phab.mercurial-scm.org/D1573

py3: use byteskwargs in sparse.py This removes several dozen failures in Python 3. Differential Revision: https://phab.mercurial-scm.org/D1482

py3: define __next__ in patch.py This needed to appease Python 3's iterator protocol. This is crasher #5 in Python 3. Differential Revision: https://phab.mercurial-scm.org/D1480

run-tests: mechanism to report exceptions during test execution Sometimes when running tests you introduce a ton of exceptions. The most extreme example of this is running Mercurial with Python 3, which currently spews thousands of exceptions when running the test harness. This commit adds an opt-in feature to run-tests.py to aggregate exceptions encountered by `hg` when running tests. When --exceptions is used, the test harness enables the "logexceptions" extension in the test environment. This extension wraps the Mercurial function to handle exceptions and writes information about the exception to a random filename in a directory defined by the test harness via an environment variable. At the end of the test harness, these files are parsed, aggregated, and a list of all unique Mercurial frames triggering exceptions is printed in order of frequency. This feature is intended to aid Python 3 development. I've only really tested it on Python 3. There is no shortage of improvements that could be made. e.g. we could write a separate file containing the exception report - maybe even an HTML report. We also don't capture which tests demonstrate the exceptions, so there's no turnkey way to test whether a code change made an exception disappear. Perfect is the enemy of good. I think the current patch is useful enough to land. Whoever uses it can send patches to imprve its usefulness. Differential Revision: https://phab.mercurial-scm.org/D1477