no update on change to plugin code, no cache, fresh install

Hi,
I installed a fresh WP locally on a Raspberry Pi.
I started to play with the Parsnip plugin code, changing it from:
$output.='<div class="parsnip">';
to
$output.='<div class="snip">';
(yeah, basic).
When I CTRL+F5 the post (even after changing and updating content), it still shows <div class=”parsnip”> in the page source.
I flushed cache, tried with another browser … still no luck.
I didn’t installed any cache plugin.
When I change post content, the content is updated (from DB) but not the div in the source code (from plugin file)!
Additionally if I make mistakes in the plugin code (like commenting a foreach), there’s no error and it still delivers the ‘old’ working version without even deactivating the plugin.
I checked the plugin file via FTP, my changes are present.
Looks like it’s using an old file version or there’s a hidden cache in WP 3.6.1?
And no, there’s no revision system or RAID on the server. It’s a Raspi 🙂

Any idea what I missed?