push: don't send a packfile when only issuing delete commands
push: don't send a packfile when only issuing delete commands

For update and create commands where all the objects are known to
exist in the remote, we must send an empty packfile. However, if all
we issue are delete commands, no packfile must be sent.

Take this into consideration for push.

Aorjoa/libgit2_maked_lib,t0xicCode/libgit2,mrksrm/Mingijura,oaastest/libgit2,MrHacky/libgit2,Aorjoa/libgit2_maked_lib,jeffhostetler/public_libgit2,MrHacky/libgit2,mrksrm/Mingijura,mcanthony/libgit2,whoisj/libgit2,yongthecoder/libgit2,leoyanggit/libgit2,mingyaaaa/libgit2,KTXSoftware/libgit2,rcorre/libgit2,leoyanggit/libgit2,oaastest/libgit2,falqas/libgit2,magnus98/TEST,whoisj/libgit2,magnus98/TEST,sygool/libgit2,JIghtuse/libgit2,nokiddin/libgit2,since2014/libgit2,zodiac/libgit2.js,stewid/libgit2,dleehr/libgit2,sim0629/libgit2,mingyaaaa/libgit2,spraints/libgit2,yosefhackmon/libgit2,Snazz2001/libgit2,leoyanggit/libgit2,since2014/libgit2,mingyaaaa/libgit2,yongthecoder/libgit2,linquize/libgit2,saurabhsuniljain/libgit2,linquize/libgit2,mrksrm/Mingijura,raybrad/libit2,skabel/manguse,since2014/libgit2,kissthink/libgit2,maxiaoqian/libgit2,t0xicCode/libgit2,KTXSoftware/libgit2,spraints/libgit2,zodiac/libgit2.js,kissthink/libgit2,Aorjoa/libgit2_maked_lib,ardumont/libgit2,jflesch/libgit2-mariadb,zodiac/libgit2.js,sim0629/libgit2,since2014/libgit2,chiayolin/libgit2,chiayolin/libgit2,kissthink/libgit2,t0xicCode/libgit2,mhp/libgit2,amyvmiwei/libgit2,mcanthony/libgit2,Corillian/libgit2,ardumont/libgit2,ardumont/libgit2,sim0629/libgit2,mingyaaaa/libgit2,chiayolin/libgit2,chiayolin/libgit2,dleehr/libgit2,amyvmiwei/libgit2,yosefhackmon/libgit2,nokiddin/libgit2,skabel/manguse,MrHacky/libgit2,magnus98/TEST,Corillian/libgit2,mhp/libgit2,Snazz2001/libgit2,jflesch/libgit2-mariadb,oaastest/libgit2,iankronquist/libgit2,kissthink/libgit2,JIghtuse/libgit2,falqas/libgit2,whoisj/libgit2,leoyanggit/libgit2,rcorre/libgit2,falqas/libgit2,saurabhsuniljain/libgit2,ardumont/libgit2,KTXSoftware/libgit2,jflesch/libgit2-mariadb,saurabhsuniljain/libgit2,mhp/libgit2,sygool/libgit2,claudelee/libgit2,rcorre/libgit2,jflesch/libgit2-mariadb,evhan/libgit2,mingyaaaa/libgit2,mingyaaaa/libgit2,KTXSoftware/libgit2,oaastest/libgit2,yosefhackmon/libgit2,evhan/libgit2,stewid/libgit2,linquize/libgit2,ardumont/libgit2,since2014/libgit2,MrHacky/libgit2,maxiaoqian/libgit2,joshtriplett/libgit2,leoyanggit/libgit2,magnus98/TEST,linquize/libgit2,dleehr/libgit2,kissthink/libgit2,Snazz2001/libgit2,swisspol/DEMO-libgit2,Corillian/libgit2,swisspol/DEMO-libgit2,skabel/manguse,jeffhostetler/public_libgit2,Tousiph/Demo1,skabel/manguse,yosefhackmon/libgit2,skabel/manguse,stewid/libgit2,chiayolin/libgit2,jeffhostetler/public_libgit2,saurabhsuniljain/libgit2,magnus98/TEST,saurabhsuniljain/libgit2,claudelee/libgit2,joshtriplett/libgit2,stewid/libgit2,evhan/libgit2,Aorjoa/libgit2_maked_lib,sygool/libgit2,oaastest/libgit2,mhp/libgit2,yongthecoder/libgit2,yongthecoder/libgit2,Tousiph/Demo1,linquize/libgit2,sim0629/libgit2,sygool/libgit2,raybrad/libit2,mrksrm/Mingijura,raybrad/libit2,raybrad/libit2,spraints/libgit2,Corillian/libgit2,mrksrm/Mingijura,claudelee/libgit2,rcorre/libgit2,spraints/libgit2,claudelee/libgit2,JIghtuse/libgit2,swisspol/DEMO-libgit2,maxiaoqian/libgit2,JIghtuse/libgit2,dleehr/libgit2,whoisj/libgit2,t0xicCode/libgit2,oaastest/libgit2,Aorjoa/libgit2_maked_lib,jeffhostetler/public_libgit2,MrHacky/libgit2,mcanthony/libgit2,swisspol/DEMO-libgit2,falqas/libgit2,mcanthony/libgit2,Snazz2001/libgit2,skabel/manguse,JIghtuse/libgit2,zodiac/libgit2.js,kenprice/libgit2,rcorre/libgit2,ardumont/libgit2,joshtriplett/libgit2,swisspol/DEMO-libgit2,amyvmiwei/libgit2,spraints/libgit2,dleehr/libgit2,Tousiph/Demo1,joshtriplett/libgit2,amyvmiwei/libgit2,mhp/libgit2,JIghtuse/libgit2,kenprice/libgit2,KTXSoftware/libgit2,mhp/libgit2,iankronquist/libgit2,KTXSoftware/libgit2,mrksrm/Mingijura,iankronquist/libgit2,iankronquist/libgit2,Tousiph/Demo1,t0xicCode/libgit2,leoyanggit/libgit2,kissthink/libgit2,whoisj/libgit2,dleehr/libgit2,nokiddin/libgit2,stewid/libgit2,rcorre/libgit2,raybrad/libit2,nokiddin/libgit2,falqas/libgit2,nokiddin/libgit2,maxiaoqian/libgit2,sim0629/libgit2,spraints/libgit2,iankronquist/libgit2,iankronquist/libgit2,kenprice/libgit2,mcanthony/libgit2,zodiac/libgit2.js,falqas/libgit2,whoisj/libgit2,evhan/libgit2,jflesch/libgit2-mariadb,stewid/libgit2,sygool/libgit2,Tousiph/Demo1,amyvmiwei/libgit2,yosefhackmon/libgit2,joshtriplett/libgit2,MrHacky/libgit2,claudelee/libgit2,yosefhackmon/libgit2,jflesch/libgit2-mariadb,jeffhostetler/public_libgit2,sim0629/libgit2,kenprice/libgit2,t0xicCode/libgit2,kenprice/libgit2,chiayolin/libgit2,nokiddin/libgit2,linquize/libgit2,claudelee/libgit2,swisspol/DEMO-libgit2,magnus98/TEST,Corillian/libgit2,maxiaoqian/libgit2,maxiaoqian/libgit2,kenprice/libgit2,sygool/libgit2,Snazz2001/libgit2,saurabhsuniljain/libgit2,amyvmiwei/libgit2,mcanthony/libgit2,yongthecoder/libgit2,Snazz2001/libgit2,yongthecoder/libgit2,Corillian/libgit2,since2014/libgit2,Tousiph/Demo1,joshtriplett/libgit2,jeffhostetler/public_libgit2