Merge branch 'nd/log-show-linear-break'

Attempts to show where a single-strand-of-pearls break in "git log"
output.

* nd/log-show-linear-break:
  log: add --show-linear-break to help see non-linear history
  object.h: centralize object flag allocation

fetch-pack.c

@@ -26,6 +26,7 @@ static int agent_supported;
 static struct lock_file shallow_lock;
 static const char *alternate_shallow_file;
 
+/* Remember to update object flag allocation in object.h */
 #define COMPLETE	(1U << 0)
 #define COMMON		(1U << 1)
 #define COMMON_REF	(1U << 2)