Upstream git.git has converted its codebase to use wildcard in
favor of fnmatch in commit 70a8fc999d (stop using fnmatch (either
native or compat), 2014-02-15). To keep our own regex-matching in
line with what git does, convert all trivial instances of
`fnmatch` usage to use `wildcard`, instead. Trivial usage is
defined to be use of `fnmatch` with either no flags or flags that
have a 1:1 equivalent in wildmatch (PATHNAME, IGNORECASE).