DatabaseCondition not cloning SelectQuery value object (documentation followup)

I couldn't find an issue reporting this bug, so here it is :
We notice that we are unable to cache a view in Commerce Kickstart without loosing some informations. (see #1691142: Make it possible to cache collection views).

This view is in charge of displaying nodes attached to the term passed as parameter and group them according to terms from another vocabulary. When cache is enabled we loose grouping informations.

Query without cache

SELECT DISTINCT taxonomy_term_data_node.tid AS taxonomy_term_data_node_tid, taxonomy_term_data_node.name AS taxonomy_term_data_node_name, taxonomy_term_data_node.vid AS taxonomy_term_data_node_vid, taxonomy_term_data_node__taxonomy_vocabulary.machine_name AS taxonomy_term_data_node__taxonomy_vocabulary_machine_name, node.nid AS nid
FROM
{node} node
LEFT JOIN (SELECT td.*, tn.nid AS nid
FROM
{taxonomy_term_data} td
LEFT JOIN {taxonomy_vocabulary} tv ON td.vid = tv.vid
LEFT JOIN {taxonomy_index} tn ON tn.tid = td.tid
WHERE (tv.machine_name IN (:db_placeholder_0)) ) taxonomy_term_data_node ON node.nid = taxonomy_term_data_node.nid
LEFT JOIN {taxonomy_vocabulary} taxonomy_term_data_node__taxonomy_vocabulary ON taxonomy_term_data_node.vid = taxonomy_term_data_node__taxonomy_vocabulary.vid
WHERE (( (node.status = 1 OR (node.uid = 1 AND 1 <> 0 AND 1 = 1) OR 1 = 1) AND (node.nid IN (SELECT tn.nid AS nid
FROM
{taxonomy_index} tn
WHERE ( (tn.tid = :db_placeholder_1) ))) ))
ORDER BY taxonomy_term_data_node_name ASC

Query with cache

SELECT DISTINCT taxonomy_term_data_node.tid AS taxonomy_term_data_node_tid, taxonomy_term_data_node.name AS taxonomy_term_data_node_name, taxonomy_term_data_node.vid AS taxonomy_term_data_node_vid, taxonomy_term_data_node__taxonomy_vocabulary.machine_name AS taxonomy_term_data_node__taxonomy_vocabulary_machine_name, node.nid AS nid
FROM
{node} node
LEFT JOIN (SELECT td.*, tn.nid AS nid
FROM
{taxonomy_term_data} td
LEFT JOIN {taxonomy_vocabulary} tv ON td.vid = tv.vid
LEFT JOIN {taxonomy_index} tn ON tn.tid = td.tid
WHERE (tv.machine_name IN (:db_placeholder_0_0)) ) taxonomy_term_data_node ON node.nid = taxonomy_term_data_node.nid
LEFT JOIN {taxonomy_vocabulary} taxonomy_term_data_node__taxonomy_vocabulary ON taxonomy_term_data_node.vid = taxonomy_term_data_node__taxonomy_vocabulary.vid
WHERE (( (node.status = 1 OR (node.uid = 1 AND 1 <> 0 AND 1 = 1) OR 1 = 1) AND (node.nid IN (SELECT tn.nid AS nid
FROM
{taxonomy_index} tn
WHERE ( (tn.tid =:db_placeholder_0_0) ))) ))
ORDER BY taxonomy_term_data_node_name ASC

After digging into views cache system I found that it's probably the fault of views_plugin_cache::get_results_key() function which enforce the view query to be compiled. Then when the query is about to be executed it is recompiled but as part of it has already been compiled, some placeholder goes wrong. And so part of the query failed, that's why we are missing some informations.

Here is the faulty line
views_plugin_cache.inc line 270 :
$build_info[$index] = (string) $query;