commands/plugin: ignore default gems when pruning
commands/plugin: ignore default gems when pruning

For modern RubyGems compatibility

sax/vagrant,gpkfr/vagrant,jberends/vagrant,Chhed13/vagrant,cgvarela/vagrant,cgvarela/vagrant,Sgoettschkes/vagrant,invernizzi-at-google/vagrant,blueyed/vagrant,tschortsch/vagrant,crashlytics/vagrant,iNecas/vagrant,darkn3rd/vagrant,nickryand/vagrant,Endika/vagrant,taliesins/vagrant,dharmab/vagrant,MiLk/vagrant,pwnall/vagrant,bdwyertech/vagrant,tbarrongh/vagrant,lonniev/vagrant,clinstid/vagrant,tschortsch/vagrant,p0deje/vagrant,muhanadra/vagrant,nickryand/vagrant,chrisvire/vagrant,PatOShea/vagrant,rivy/vagrant,crashlytics/vagrant,legal90/vagrant,ferventcoder/vagrant,tbarrongh/vagrant,gbarberi/vagrant,apertoso/vagrant,tjanez/vagrant,philoserf/vagrant,bdwyertech/vagrant,justincampbell/vagrant,benh57/vagrant,legal90/vagrant,tschortsch/vagrant,petems/vagrant,aneeshusa/vagrant,patrys/vagrant,MiLk/vagrant,miguel250/vagrant,philoserf/vagrant,justincampbell/vagrant,jtopper/vagrant,vamegh/vagrant,wkolean/vagrant,taliesins/vagrant,invernizzi-at-google/vagrant,zsjohny/vagrant,jtopper/vagrant,PatOShea/vagrant,lukebakken/vagrant,taliesins/vagrant,muhanadra/vagrant,denisbr/vagrant,gpkfr/vagrant,Endika/vagrant,johntron/vagrant,evverx/vagrant,marxarelli/vagrant,gpkfr/vagrant,clinstid/vagrant,genome21/vagrant,otagi/vagrant,fnewberg/vagrant,ianmiell/vagrant,pwnall/vagrant,marxarelli/vagrant,aaam/vagrant,tomfanning/vagrant,fnewberg/vagrant,juiceinc/vagrant,bshurts/vagrant,dustymabe/vagrant,lukebakken/vagrant,vamegh/vagrant,darkn3rd/vagrant,sax/vagrant,kamigerami/vagrant,sni/vagrant,otagi/vagrant,jmanero/vagrant,signed8bit/vagrant,MiLk/vagrant,evverx/vagrant,aneeshusa/vagrant,jkburges/vagrant,taliesins/vagrant,benh57/vagrant,mpoeter/vagrant,senglin/vagrant,legal90/vagrant,wkolean/vagrant,teotihuacanada/vagrant,mkuzmin/vagrant,myrjola/vagrant,mkuzmin/vagrant,vamegh/vagrant,modulexcite/vagrant,wangfakang/vagrant,janek-warchol/vagrant,jfchevrette/vagrant,gitebra/vagrant,mwarren/vagrant,theist/vagrant,kalabiyau/vagrant,miguel250/vagrant,tknerr/vagrant,legal90/vagrant,tschortsch/vagrant,Endika/vagrant,shtouff/vagrant,channui/vagrant,miguel250/vagrant,lonniev/vagrant,channui/vagrant,jfchevrette/vagrant,jean/vagrant,johntron/vagrant,vamegh/vagrant,carlosefr/vagrant,wkolean/vagrant,invernizzi-at-google/vagrant,gbarberi/vagrant,mwrock/vagrant,shtouff/vagrant,chrisvire/vagrant,darkn3rd/vagrant,muhanadra/vagrant,ferventcoder/vagrant,chrisvire/vagrant,signed8bit/vagrant,carlosefr/vagrant,jhoblitt/vagrant,TheBigBear/vagrant,mpoeter/vagrant,sax/vagrant,jean/vagrant,benizi/vagrant,mitchellh/vagrant,tomfanning/vagrant,miguel250/vagrant,aaam/vagrant,tjanez/vagrant,doy/vagrant,jmanero/vagrant,Avira/vagrant,krig/vagrant,gajdaw/vagrant,sferik/vagrant,Avira/vagrant,gajdaw/vagrant,chrisroberts/vagrant,h4ck3rm1k3/vagrant,apertoso/vagrant,lukebakken/vagrant,bryson/vagrant,kamazee/vagrant,modulexcite/vagrant,kamigerami/vagrant,gitebra/vagrant,tbarrongh/vagrant,blueyed/vagrant,evverx/vagrant,dharmab/vagrant,benizi/vagrant,tjanez/vagrant,dhoer/vagrant,jberends/vagrant,kamigerami/vagrant,Sgoettschkes/vagrant,PatrickLang/vagrant,sax/vagrant,sferik/vagrant,pwnall/vagrant,bheuvel/vagrant,doy/vagrant,ArloL/vagrant,lukebakken/vagrant,philwrenn/vagrant,mwrock/vagrant,tomfanning/vagrant,Chhed13/vagrant,mitchellh/vagrant,signed8bit/vagrant,bheuvel/vagrant,tbarrongh/vagrant,Ninir/vagrant,shtouff/vagrant,BlakeMesdag/vagrant,Chhunlong/vagrant,dharmab/vagrant,stephancom/vagrant,janek-warchol/vagrant,Ninir/vagrant,jtopper/vagrant,PatOShea/vagrant,aaam/vagrant,blueyed/vagrant,bdwyertech/vagrant,justincampbell/vagrant,ArloL/vagrant,sni/vagrant,senglin/vagrant,Avira/vagrant,Sgoettschkes/vagrant,obnoxxx/vagrant,pwnall/vagrant,loren-osborn/vagrant,p0deje/vagrant,chrisvire/vagrant,teotihuacanada/vagrant,johntron/vagrant,apertoso/vagrant,bshurts/vagrant,jberends/vagrant,BlakeMesdag/vagrant,otagi/vagrant,mitchellh/vagrant,doy/vagrant,jfchevrette/vagrant,kalabiyau/vagrant,philwrenn/vagrant,marxarelli/vagrant,dustymabe/vagrant,iNecas/vagrant,modulexcite/vagrant,tomfanning/vagrant,mkuzmin/vagrant,benizi/vagrant,gitebra/vagrant,benizi/vagrant,kamazee/vagrant,h4ck3rm1k3/vagrant,myrjola/vagrant,modulexcite/vagrant,PatrickLang/vagrant,tbriggs-curse/vagrant,tbriggs-curse/vagrant,loren-osborn/vagrant,ianmiell/vagrant,kamazee/vagrant,gpkfr/vagrant,bshurts/vagrant,ianmiell/vagrant,benh57/vagrant,blueyed/vagrant,myrjola/vagrant,kamigerami/vagrant,zsjohny/vagrant,Avira/vagrant,mwrock/vagrant,Endika/vagrant,nickryand/vagrant,genome21/vagrant,gitebra/vagrant,denisbr/vagrant,janek-warchol/vagrant,myrjola/vagrant,mwarren/vagrant,carlosefr/vagrant,aaam/vagrant,p0deje/vagrant,obnoxxx/vagrant,jtopper/vagrant,philoserf/vagrant,tbriggs-curse/vagrant,tknerr/vagrant,mwarren/vagrant,dustymabe/vagrant,krig/vagrant,dhoer/vagrant,cgvarela/vagrant,invernizzi-at-google/vagrant,h4ck3rm1k3/vagrant,muhanadra/vagrant,gbarberi/vagrant,stephancom/vagrant,zsjohny/vagrant,mitchellh/vagrant,philwrenn/vagrant,TheBigBear/vagrant,zsjohny/vagrant,Chhunlong/vagrant,apertoso/vagrant,tknerr/vagrant,gbarberi/vagrant,stephancom/vagrant,denisbr/vagrant,bheuvel/vagrant,kalabiyau/vagrant,Chhed13/vagrant,jean/vagrant,theist/vagrant,cgvarela/vagrant,darkn3rd/vagrant,jfchevrette/vagrant,dhoer/vagrant,rivy/vagrant,tknerr/vagrant,chrisroberts/vagrant,PatrickLang/vagrant,philoserf/vagrant,PatrickLang/vagrant,loren-osborn/vagrant,mkuzmin/vagrant,tbriggs-curse/vagrant,philwrenn/vagrant,bryson/vagrant,TheBigBear/vagrant,h4ck3rm1k3/vagrant,BlakeMesdag/vagrant,mwrock/vagrant,jkburges/vagrant,senglin/vagrant,teotihuacanada/vagrant,ArloL/vagrant,Chhunlong/vagrant,genome21/vagrant,chrisroberts/vagrant,tjanez/vagrant,jean/vagrant,obnoxxx/vagrant,wangfakang/vagrant,fnewberg/vagrant,bshurts/vagrant,stephancom/vagrant,chrisroberts/vagrant,jmanero/vagrant,crashlytics/vagrant,gajdaw/vagrant,ferventcoder/vagrant,juiceinc/vagrant,mwarren/vagrant,sni/vagrant,bheuvel/vagrant,nickryand/vagrant,wangfakang/vagrant,johntron/vagrant,doy/vagrant,justincampbell/vagrant,sideci-sample/sideci-sample-vagrant,wangfakang/vagrant,janek-warchol/vagrant,Ninir/vagrant,sideci-sample/sideci-sample-vagrant,krig/vagrant,ianmiell/vagrant,jhoblitt/vagrant,rivy/vagrant,benh57/vagrant,crashlytics/vagrant,patrys/vagrant,bryson/vagrant,rivy/vagrant,petems/vagrant,bdwyertech/vagrant,krig/vagrant,dharmab/vagrant,Sgoettschkes/vagrant,teotihuacanada/vagrant,juiceinc/vagrant,senglin/vagrant,fnewberg/vagrant,ferventcoder/vagrant,theist/vagrant,carlosefr/vagrant,kalabiyau/vagrant,loren-osborn/vagrant,iNecas/vagrant,jkburges/vagrant,TheBigBear/vagrant,juiceinc/vagrant,clinstid/vagrant,patrys/vagrant,jkburges/vagrant,patrys/vagrant,dhoer/vagrant,channui/vagrant,sideci-sample/sideci-sample-vagrant,jberends/vagrant,genome21/vagrant,sni/vagrant,otagi/vagrant,jhoblitt/vagrant,bryson/vagrant,dustymabe/vagrant,mpoeter/vagrant,sferik/vagrant,jmanero/vagrant,jhoblitt/vagrant,shtouff/vagrant,Chhed13/vagrant,aneeshusa/vagrant,petems/vagrant,denisbr/vagrant,theist/vagrant,Chhunlong/vagrant,ArloL/vagrant,lonniev/vagrant,aneeshusa/vagrant,lonniev/vagrant,wkolean/vagrant,mpoeter/vagrant,petems/vagrant,signed8bit/vagrant,kamazee/vagrant,marxarelli/vagrant,PatOShea/vagrant