Maven artifacts no longer available via non-TLS which breaks ABCL-ASDF

[Mark Evenson]

Sometime in the last month, the Maven central repository has stopped serving non-TLS content.  This change badly borks ABCL-ASDF’s use of Maven which has utilized the non-TLS version of the Maven central repository since its inception, which means that previous versions of ABCL will mysteriously stop working without one having changed any code.  The error reported by ABCL is obscure, as the actual error reported by the Maven Aether class is not present anywhere in the thrown exception but rather only written to the file-system under the <file:~/.m2/> hierarchy.  Initially, the error reported by ABCL resembled ones in the past which involved incompatible releases of the Maven Aether interfaces which caused me a fair amount of confusion in diagnosing this problem. 

Solutions:

1) One may build ABCL from source with the [required patch][1][2]

2) The bug only affects downloading artifacts, not using the local cache present under <file:~/.m2/>, so as long as one doesn’t “go to the network”, one can use locally present artifacts without problems.  One could use the `mvn` command-line interface to download artifacts for ABCL to use.  

3) One may patch an instance of ABCL without recompilation via the following code at the REPL or placed in <file:~/.abclrc>

    (require :abcl-contrib)
    (asdf:load-system :abcl-asdf)
    (setf abcl-asdf::*default-repository* "https://repo1.maven.org/maven2/“)

[1]: https://github.com/armedbear/abcl/commit/42abe93f4170ee30c92ba2507780cfba06f0f8e5
[2]: https://abcl.org/trac/changeset/15229



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