Romt

=============

- Fix detection of toolchain targets in the presence of artifacts shared across
targets. Previously, a given target was detected whenever any one of that
target's artifact files was found to be present. This algorithm is
insufficient when an artifact file may be shared across different targets.
Instead, a target is now detected with either *all* artifacts for that target
are present, or when at least one of the target's artifacts is present and is
unique to that target (not shared with other targets). The incorrect target
detection could lead to ``MissingFileError`` exceptions when unpacking a
toolchain archive whenever targets not present in the archive share artifact
files with targets present in the archive.

- Update list of known targets for ``rustup``.

=============

- Fix issue 13 regarding duplicate toolchain artifact URLs. Some distinct
toolchain artifacts may share the same download URL (e.g.,
``.../rust-docs-nightly-x86_64-unknown-linux-gnu.tar.xz`` is shared across
several other processor variants). Before version 0.3.0, this was handled
naturally by the sequential nature of the download operation, but the new
asynchronous support from 0.3.0 failed to account for the possible
duplication.

=============

- Fix issue 12 causing the below error with ``romt crate import`` on Windows::

INDEX remote ``origin`` must have ``url`` as a local file

Romt requires the URL to be a local path (e.g., ``/path/to/origin.bundle``)
instead of a URL with a schema (e.g., ``https://server/path``). The check for
URL schemas was overzealous. URLs with a leading ``schema:`` prefix should be
rejected, but Windows paths with drive letters such as
``c:/path/to/origin.bundle`` are local; the ``c:`` drive letter should not be
considered to be a ``schema:`` prefix. Single-character schema-like prefixes
are no longer treated as errors.

- Clarify quick-start instructions, pointing out steps which are one-time only.

- Add probe for Alpine Linux's default location for ``git-http-backend``
(``/usr/libexec/git-core/git-http-backend``) in addition to the more common
location (``/usr/lib/git-core/git-http-backend``). This eliminates the need
for manual configuration with Alpine (see issue 11).

- Improve exception messages. For `DownloadError` in particular, embed the
`repr()` of the associated exception from `httpx` to aid in debugging
`httpx`-related errors (see also issue 10 for more debugging of `httpx`
proxy-related issues).

- Support ``{prefix}`` and ``{lowerprefix}`` in ``crate --crates-url``.

- Honor ``toolchain --no-signature`` for ``toolchain fixup`` (mainly for
testing).

=============

- Fix ``romt crate --keep-going`` to correctly handle ``403 Forbidden`` and
other HTTP status failures (thanks to Anthony Gray,
https://github.com/f34rt3hbunn3h).

When porting from `requests` to `httpx`, the exception handling in the
`Downloader` class was incorrectly switched from the ``requests`` library's
``RequestException`` base class to the ``httpx`` library's ``RequestError``
class; the former is the base class for all of the exceptions in ``requests``,
whereas the latter doesn't cover all exceptions in ``httpx``. This fix
switches the exception handler to properly use ``httpx.HTTPError`` to catch
all `httpx` library exceptions.

References:
- https://docs.python-requests.org/en/master/_modules/requests/exceptions/
- https://www.python-httpx.org/exceptions/

=============

- Add support for multiple simultaneous download jobs via ``--num-jobs``,
enabled by switching from the ``requests`` package to ``httpx``.

- Drop support for Python 3.5, as ``httpx`` requires at least Python 3.6.

=============

- Fix support for Python 3.5, converting several instances of ``pathlib.Path``
to ``str`` for use with functions like ``open()``.