Strange behavior RewriteCond on Apache 2.2

working .htaccess config:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-l
RewriteCond %{REQUEST_URI} ^thumbs/(.*)$
RewriteRule ^(.+)$ /index.php [L,QSA]

All 404 queries to /thumbs/ folder not must be catched by /index.php script. Why top .htaccess config work and bottom config not work?

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-l
RewriteCond %{REQUEST_URI} !^/thumbs/(.*)$
RewriteRule ^(.+)$ /index.php开发者_C百科 [L,QSA]

Apache 2.2.9, Debian

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REQUEST_URI contains the requested URI path and does always start with a slash.

So the pattern ^thumbs/(.*)$ does never match as it’s missing the leading /. But the other condition, !^/thumbs/(.*)$, should match every request that’s URI path does not start with /thumbs/.

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I think it's because the first slash in

RewriteCond %{REQUEST_URI} !^/thumbs/(.*)$