Merge branch 'jc/rerere-modern-strbuf-handling' into next

Code clean-up overdue by 19 years.

* jc/rerere-modern-strbuf-handling:
  cocci: strbuf.buf is never NULL
  rerere: update to modern representation of empty strbufs

diff --cc rerere.c
Simple merge

diff --cc tools/coccinelle/strbuf.cocci
index 83bd93be5fce8dc43e5314c111baa4b2df7fb29f,13f0ad267902f5ba46aefabe50f455cee6289c25..f5861283297acda05e1045d0d5e6e25731a8f089
--- 1/tools/coccinelle/strbuf.cocci
--- 2/contrib/coccinelle/strbuf.cocci
+++ b/tools/coccinelle/strbuf.cocci
@@@ -61,13 -61,9 +61,20 @@@ expression E1, E2
  - strbuf_addstr(E1, real_path(E2));
  + strbuf_add_real_path(E1, E2);
  
 +@@
 +identifier fn, param;
 +@@
 +  fn(...,
 +- struct strbuf param
 ++ struct strbuf *param
 +  ,...)
 +  {
 +  ...
 +  }
++
+ // In modern codebase, .buf member of an empty strbuf is not NULL.
+ @@
+ struct strbuf SB;
+ @@
+ - SB.buf ? SB.buf : ""
+ + SB.buf