I found a nice new, rarely trigger Magento bug.

In one of our projects, we have an example file to create new products:

data-upgrade-example-new-product-import.php

Beside this we had data scripts:

data-install-1.0.1.php
data-upgrade-1.0.0-1.0.1.php
data-upgrade-1.0.5-1.0.6.php

Unfortunately data-upgrade-1.0.5-1.0.6.php didn't fire.

It took me a while, but I found the problem:

// \Mage_Core_Model_Resource_Setup::_getModifySqlFiles
protected function _getModifySqlFiles($actionType, $fromVersion, $toVersion, $arrFiles)
{
    $arrRes = array();
    switch ($actionType) {

        // ... 

        case self::TYPE_DB_UPGRADE:
        case self::TYPE_DATA_UPGRADE:
            uksort($arrFiles, 'version_compare');
            foreach ($arrFiles as $version => $file) {
                $versionInfo = explode('-', $version);

                // In array must be 2 elements: 0 => version from, 1 => version to
                if (count($versionInfo)!=2) {
                    break;
                }

in $arrFiles we find an array with all files in the data dir which match a certain regex in \Mage_Core_Model_Resource_Setup::_getAvailableDataFiles. In short, when the files starts with data-.

The problem is, that data-upgrade-example-new-product-import.php doesn't meet the if (count($versionInfo)!=2) check and then break is called, which kills the complete loop, but should only be continue;.

So either we hack the core or rename the data-upgrade-example-new-product-import.php, I decided for renaming.