Dubious code in pg_rewind's process_target_file()

scan-build complains that "exists = false" is a dead store,
which it is:

process_target_file(const char *path, file_type_t type, size_t oldsize,
const char *link_target)
{
bool exists;
...

if (lstat(localpath, &statbuf) < 0)
{
if (errno != ENOENT)
pg_fatal("could not stat file \"%s\": %s\n",
localpath, strerror(errno));

exists = false;
}

...
exists = (bsearch(&key_ptr, map->array, map->narray, sizeof(file_entry_t *),
path_cmp) != NULL);

It looks to me like we could replace "exists = false" with "return",
rather than uselessly constructing a FILE_ACTION_REMOVE entry for
a file we've already proven is not there. This seems to have been
copy-and-pasted from process_source_file, without much thought for
the fact that the situations are quite different.

regards, tom lane