Handle empty author names

modules/git/signature_gogit.go

@@ -30,7 +30,9 @@ type Signature = object.Signature
 func newSignatureFromCommitline(line []byte) (_ *Signature, err error) {
 sig := new(Signature)
 emailStart := bytes.IndexByte(line, '<')
-sig.Name = string(line[:emailStart-1])
+if emailStart > 0 { // Empty name has already occurred, even if it shouldn't
+sig.Name = string(line[:emailStart-1])
+}
 emailEnd := bytes.IndexByte(line, '>')
 sig.Email = string(line[emailStart+1 : emailEnd])
 

modules/git/signature_nogogit.go

@@ -51,7 +51,9 @@ func newSignatureFromCommitline(line []byte) (sig *Signature, err error) {
 return
 }
 
-sig.Name = string(line[:emailStart-1])
+if emailStart > 0 { // Empty name has already occurred, even if it shouldn't
+sig.Name = string(line[:emailStart-1])
+}
 sig.Email = string(line[emailStart+1 : emailEnd])
 
 hasTime := emailEnd+2 < len(line)