As a developer I want to change environment variables with drush

As it happens, I've created a patch here that adds the drush commands:

 solr-get-env-id       Get the default Apache Solr environment id                                             
 solr-get-env-name     Get the default Apache Solr environment name, uses the default environment by default. 
 solr-get-env-url      Get the default Apache Solr environment url, uses the default environment by default.  
 solr-set-env-url      Set the url for an Apache Solr environment, uses the default environment by default.

Used like so:

example » drush solr-get-env-id
solr
example » drush solr-get-env-name
Production

example » drush solr-get-env-url
http://secondary-solr:8983/solr/drupal-site-example

example » drush solr-set-env-url http://primary-solr:8983/solr/drupal-site-example
example » drush solr-get-env-url
http://primary-solr:8983/solr/drupal-site-example

Oops, lets try that again with --relative.

*sigh*, lets try that again, against 7.x-1.x.

If possible, I would prefer for this patch to be committed as a first step, then perhaps the possibility of other commands could be handled in separate feature requests when people have specific use cases they would like covered.