[FIX] QWeb2: fix xml string detection
[FIX] QWeb2: fix xml string detection

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extra : convert_revision : fme%40openerp.com-20110505093853-1ppk2dwld2a5ibbt

MarkusTeufelberger/openerp-web,splbio/openerp-web,MarkusTeufelberger/openerp-web,vnc-biz/openerp-web,vnc-biz/openerp-web,gisce/openerp-web,gisce/openerp-web,gisce/openerp-web,splbio/openerp-web,MarkusTeufelberger/openerp-web,vnc-biz/openerp-web,vnc-biz/openerp-web,splbio/openerp-web