fix location sanitizing with parser 'future'
fix location sanitizing with parser 'future'

With parser 'future', a '\\' counts as one backslash whereas with
parser 'current' it's two. Therefore with 'future' only one gets passed
to regsubst which in turn aborts with

 Error: regsubst(): Bad regular expression `\'

The 'future' behaviour is indeed the correct one but 'current' won't be
fixed either. Therefore, use "\\\\" which produces two backslashes with
both parser (ref: https://tickets.puppetlabs.com/browse/PUP-1814).

DSI-Ville-Noumea/puppet-nginx,danieldreier/puppet-nginx,bulletproofnetworks/puppet-nginx,voxpupuli/puppet-nginx,teran/puppet-nginx,jhoblitt/puppet-nginx,thumby/puppet-nginx,rdeknijf/puppet-nginx,RewardGateway/puppet-nginx,ResignationMedia/puppet-nginx,thumby/puppet-nginx,icann-dns/puppet-nginx,danieldreier/puppet-nginx,Jimdo/puppet-nginx,apa-it/puppet-nginx,Griphon/puppet-nginx,amitsaha/puppet-nginx,bulletproofnetworks/puppet-nginx,jhoblitt/puppet-nginx,rdeknijf/puppet-nginx,erikanderson/puppet-nginx,jfryman/puppet-nginx,RewardGateway/puppet-nginx,xaque208/puppet-nginx,Jimdo/puppet-nginx,icann-dns/puppet-nginx,ResignationMedia/puppet-nginx,apa-it/puppet-nginx,teran/puppet-nginx,bastelfreak/puppet-nginx,blackcobra1973/puppet-nginx,sanoma-technology/puppet-nginx,blackcobra1973/puppet-nginx,jd-daniels/puppet-nginx,mmickan/puppet-nginx,raphink/puppet-nginx,mmickan/puppet-nginx,Yelp/puppet-nginx,syscollective/puppet-nginx,kwolf/puppet-nginx,kronos-pbrideau/puppet-nginx,cwood/puppet-nginx,Griphon/puppet-nginx,erikanderson/puppet-nginx,voxpupuli/puppet-nginx,syscollective/puppet-nginx,kwolf/puppet-nginx,ckaenzig/puppet-nginx,jjkoletar/puppet-nginx,xaque208/puppet-nginx,jjkoletar/puppet-nginx,sanoma-technology/puppet-nginx,jd-daniels/puppet-nginx,maxenced/puppet-nginx,cwood/puppet-nginx,bastelfreak/puppet-nginx,jordiclariana/puppet-nginx,DSI-Ville-Noumea/puppet-nginx,jordiclariana/puppet-nginx,hbog/puppet-nginx,maxenced/puppet-nginx,MelanieGault/puppet-nginx,jfryman/puppet-nginx,kronos-pbrideau/puppet-nginx,amitsaha/puppet-nginx,MelanieGault/puppet-nginx,hbog/puppet-nginx