refspec: set err message on invalid refspec
refspec: set err message on invalid refspec

If a refspec could not be parsed, the git_refspec__parse function would
return an error value but would not provide additional error information
for the callers. This commit amends that function to set a more useful
error message.

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