Bugfix Issue 1693 tree get_subtree static leak

Bugfix: tree::_get_subtree() static state causes cross-call contamination

Issue

#1693 — tree::_get_subtree(): 'static $my' is process-wide, so one direct call silently empties the subtree of the next (tree.class.php:873)

Root Cause

• tree::_get_subtree() declared static $my (lib/functions/tree.class.php:873-884), shared across all instances and calls in the same PHP process.
• Defaults initialized only once (if(!$my)).
• Subsequent calls did array_merge($my['filters'], (array)$filters) and array_merge($my['options'], (array)$options); keys omitted by the caller were preserved from the previous call, causing cross-call/options contamination.
• When a call with order_cfg=rspec ran first, a later bare-options call retained rspec options and returned the wrong subtree set.

This was the twin of #1607 (which fixed _get_subtree_rec()).

Fix

Applied minimal change in lib/functions/tree.class.php:

• Removed static $my and one-time init in _get_subtree().
• Initialize local $defaultsFilters and $defaultsOptions on every call.
• Use array_merge($defaultsFilters, (array)$filters) and array_merge($defaultsOptions, (array)$options).
• Pass merged context in recursion ($my['filters'], $my['options']) instead of raw args.

Verification

Repro script tmp/verify_leak5.php:

• Before fix: 0:13, 1:2, 2:2 (leak — call 2 matched call 1, not pristine)
• After fix: 0:13, 1:2, 2:13 (fixed — call 2 equals pristine)

Files Changed

• lib/functions/tree.class.php (removed static state, per-call defaults, recursion uses merged context)

Commit

• 487c7ccc1 fix(tree): remove process-wide static state in _get_subtree() causing cross-call contamination