Use mirrors for tarballs

[vbraun]

This ticket rewrites the sage-download-file script in pure Python. It is, first of all, a drop-in replacement of the current script. But it is now also aware of our tarballs, so you can just write e.g.

sage-download-file sympy-0.7.4.tar.gz

and it will download that tarball from the fastest mirror and verify its checksum.

CC: @ohanar @sagetrac-tmonteil @haraldschilly

Component: build

Author: Volker Braun

Branch/Commit: d79364b

Reviewer: Volker Braun

Issue created by migration from https://trac.sagemath.org/ticket/15642

[vbraun]

Branch: u/vbraun/use_mirrors_for_tarballs

[sagetrac-git]

Commit: dd4abcb

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

3967968	Merge tag '6.1.beta4' into 'u/vbraun/use_mirrors_for_tarballs'
dd4abcb	py3 fix, also try testing packages

[vbraun]

Description changed:

--- 
+++ 
@@ -1 +1,6 @@
+This ticket rewrites the `sage-download-file` script in pure Python. It is, first of all, a drop-in replacement of the current script. But it is now also aware of our tarballs, so you can just write e.g.
 
+```
+sage-download-file sympy-0.7.4.tar.gz
+```
+and it will download that tarball from the fastest mirror and verify its checksum.

[sagetrac-git]

Changed commit from dd4abcb to b1ef0b6

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

b1ef0b6

prefer SAGE_DISTFILES for upstream directory

[ohanar]

comment:6

I would replace the regex in _parse_name with something like

(?P<base>(?:[^-]|-(?!\d))*)-(?P<version>.*)\.(?P<ext>tar.*|zip|tgz)

(We may as well support more general package names, even if our restrictive naming convention doesn't allow it at the moment.)

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

cd155cf

more general tarball regex

[sagetrac-git]

Changed commit from b1ef0b6 to cd155cf

[ohanar]

Author: Volker Braun