tree cache: loosen negative entry count check
tree cache: loosen negative entry count check

While C Git has been writing entry count -1 (ie. never other negative
numbers) as invalid since day 1, it accepts all negative entry counts
as invalid. JGit follows the same rule. libgit2 should also follow, or
the index that works with C Git or JGit may someday be rejected by
libgit2.

Other reimplementations like dulwich and grit have not bothered with
parsing or writing tree cache.

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