Merge branch 'th/diff-no-index-fixes'

"git diff --no-index" did not correctly handle relative paths and
did not give correct exit codes when run under "--quiet" option.

* th/diff-no-index-fixes:
  diff-no-index: exit(1) if 'diff --quiet <repo file> <external file>' finds changes
  diff: handle relative paths in no-index

cache.h

@@ -413,6 +413,7 @@ extern void verify_filename(const char *prefix,
 			    const char *name,
 			    int diagnose_misspelt_rev);
 extern void verify_non_filename(const char *prefix, const char *name);
+extern int path_inside_repo(const char *prefix, const char *path);
 
 #define INIT_DB_QUIET 0x0001