Properly parse first line in ReceivePack with no '\0'

Change-Id: Ic98e17aff4e4b3c3fa0359082bab689e4522e3d7

org.eclipse.jgit/src/org/eclipse/jgit/transport/ReceivePack.java

@@ -115,8 +115,9 @@ public class ReceivePack {
 			if (nul >= 0) {
 				for (String c : line.substring(nul + 1).split(" "))
 					caps.add(c);
-			}
-			this.line = line.substring(0, nul);
+				this.line = line.substring(0, nul);
+			} else
+				this.line = line;
 			this.capabilities = Collections.unmodifiableSet(caps);
 		}