When previewing a page creation, populate url_path.
When previewing a page creation, populate url_path.

This ensures that Page.dummy_request can infer a sensible hostname rather than falling back on example.com, which fails when ALLOWED_HOSTS is enforced.

helenwarren/pied-wagtail,rv816/wagtail,kurtw/wagtail,Pennebaker/wagtail,KimGlazebrook/wagtail-experiment,nutztherookie/wagtail,nilnvoid/wagtail,dresiu/wagtail,rv816/wagtail,kurtrwall/wagtail,100Shapes/wagtail,takeshineshiro/wagtail,tangentlabs/wagtail,takeflight/wagtail,inonit/wagtail,nealtodd/wagtail,wagtail/wagtail,darith27/wagtail,chimeno/wagtail,gogobook/wagtail,hanpama/wagtail,inonit/wagtail,nealtodd/wagtail,Klaudit/wagtail,benemery/wagtail,kaedroho/wagtail,WQuanfeng/wagtail,wagtail/wagtail,WQuanfeng/wagtail,Tivix/wagtail,rsalmaso/wagtail,bjesus/wagtail,benjaoming/wagtail,serzans/wagtail,takeflight/wagtail,mayapurmedia/wagtail,jorge-marques/wagtail,Klaudit/wagtail,zerolab/wagtail,taedori81/wagtail,Toshakins/wagtail,nilnvoid/wagtail,hamsterbacke23/wagtail,100Shapes/wagtail,taedori81/wagtail,Toshakins/wagtail,nutztherookie/wagtail,timorieber/wagtail,nrsimha/wagtail,FlipperPA/wagtail,nealtodd/wagtail,chrxr/wagtail,jorge-marques/wagtail,zerolab/wagtail,benemery/wagtail,davecranwell/wagtail,chimeno/wagtail,takeflight/wagtail,kaedroho/wagtail,inonit/wagtail,stevenewey/wagtail,tangentlabs/wagtail,nrsimha/wagtail,chimeno/wagtail,kurtrwall/wagtail,quru/wagtail,bjesus/wagtail,stevenewey/wagtail,mixxorz/wagtail,m-sanders/wagtail,kurtw/wagtail,m-sanders/wagtail,Toshakins/wagtail,kaedroho/wagtail,marctc/wagtail,100Shapes/wagtail,iho/wagtail,nilnvoid/wagtail,nilnvoid/wagtail,Tivix/wagtail,zerolab/wagtail,rv816/wagtail,WQuanfeng/wagtail,jnns/wagtail,mjec/wagtail,benjaoming/wagtail,jnns/wagtail,davecranwell/wagtail,Tivix/wagtail,rjsproxy/wagtail,lojack/wagtail,chimeno/wagtail,hamsterbacke23/wagtail,mjec/wagtail,rjsproxy/wagtail,rsalmaso/wagtail,janusnic/wagtail,stevenewey/wagtail,JoshBarr/wagtail,quru/wagtail,janusnic/wagtail,serzans/wagtail,timorieber/wagtail,taedori81/wagtail,rjsproxy/wagtail,chimeno/wagtail,m-sanders/wagtail,taedori81/wagtail,Pennebaker/wagtail,Pennebaker/wagtail,FlipperPA/wagtail,rv816/wagtail,janusnic/wagtail,stevenewey/wagtail,rsalmaso/wagtail,mikedingjan/wagtail,nimasmi/wagtail,kurtw/wagtail,willcodefortea/wagtail,gogobook/wagtail,jordij/wagtail,tangentlabs/wagtail,iho/wagtail,lojack/wagtail,mephizzle/wagtail,nimasmi/wagtail,hanpama/wagtail,nealtodd/wagtail,gogobook/wagtail,KimGlazebrook/wagtail-experiment,mixxorz/wagtail,dresiu/wagtail,kaedroho/wagtail,iansprice/wagtail,gasman/wagtail,chrxr/wagtail,mephizzle/wagtail,timorieber/wagtail,Klaudit/wagtail,benjaoming/wagtail,wagtail/wagtail,helenwarren/pied-wagtail,rsalmaso/wagtail,m-sanders/wagtail,kaedroho/wagtail,gasman/wagtail,jordij/wagtail,WQuanfeng/wagtail,wagtail/wagtail,inonit/wagtail,kurtw/wagtail,helenwarren/pied-wagtail,iansprice/wagtail,KimGlazebrook/wagtail-experiment,takeshineshiro/wagtail,nimasmi/wagtail,jordij/wagtail,zerolab/wagtail,kurtrwall/wagtail,benemery/wagtail,iho/wagtail,hamsterbacke23/wagtail,marctc/wagtail,jordij/wagtail,iansprice/wagtail,marctc/wagtail,quru/wagtail,jorge-marques/wagtail,iansprice/wagtail,rsalmaso/wagtail,willcodefortea/wagtail,bjesus/wagtail,davecranwell/wagtail,chrxr/wagtail,bjesus/wagtail,takeflight/wagtail,torchbox/wagtail,rjsproxy/wagtail,JoshBarr/wagtail,darith27/wagtail,mixxorz/wagtail,gasman/wagtail,jnns/wagtail,serzans/wagtail,jorge-marques/wagtail,serzans/wagtail,benemery/wagtail,mixxorz/wagtail,nutztherookie/wagtail,Tivix/wagtail,darith27/wagtail,takeshineshiro/wagtail,janusnic/wagtail,hanpama/wagtail,gasman/wagtail,lojack/wagtail,gasman/wagtail,mayapurmedia/wagtail,Klaudit/wagtail,Toshakins/wagtail,iho/wagtail,willcodefortea/wagtail,jnns/wagtail,torchbox/wagtail,mjec/wagtail,wagtail/wagtail,mephizzle/wagtail,kurtrwall/wagtail,nrsimha/wagtail,KimGlazebrook/wagtail-experiment,mikedingjan/wagtail,takeshineshiro/wagtail,gogobook/wagtail,mephizzle/wagtail,dresiu/wagtail,marctc/wagtail,nimasmi/wagtail,nrsimha/wagtail,thenewguy/wagtail,thenewguy/wagtail,timorieber/wagtail,JoshBarr/wagtail,thenewguy/wagtail,quru/wagtail,thenewguy/wagtail,thenewguy/wagtail,hamsterbacke23/wagtail,FlipperPA/wagtail,mayapurmedia/wagtail,davecranwell/wagtail,mayapurmedia/wagtail,nutztherookie/wagtail,darith27/wagtail,mikedingjan/wagtail,chrxr/wagtail,dresiu/wagtail,hanpama/wagtail,torchbox/wagtail,JoshBarr/wagtail,tangentlabs/wagtail,zerolab/wagtail,willcodefortea/wagtail,mixxorz/wagtail,FlipperPA/wagtail,mjec/wagtail,taedori81/wagtail,jorge-marques/wagtail,benjaoming/wagtail,dresiu/wagtail,torchbox/wagtail,Pennebaker/wagtail,mikedingjan/wagtail