i'm not the mod_rewrite-expert, but in my doku they use RewriteBase for the Start-Folder
No RewriteBase-info or a RewriteBase like a simple slash like / means: start in the document-root of this server
a rewrite rule like this
RewriteRule ^([\/\sa-zA-Z0-9._-]+)$ /short.php?_wb=$1 [QSA,L]
means also: start in the document root
a rewrite rule without leading slash means: start in the same folder like the htaccess btw the index.php in the root of wb
Everything works fine, if i dont use the leading shlash, with or without RewriteBase
please correct me, if i'm wrong