- IsReadmeFile now takes (name, mode) and only matches regular file
blobs (filemode.Regular/Executable). A directory or symlink named
"readme" was being picked up by tree handlers, which then tried to
fetch its blob and 503'd.
- ReadmePattern matches by convention (^readme(?:[._-].+)?$) rather
than a fixed extension set. README.rst, README.org, README-old, etc.
now surface on index/tree pages and fall through to FormatText in
GetFormat for plaintext rendering.
- pages.RepoIndex and pages.RepoTree route through markup.GetFormat
instead of hardcoded extension switches, so the markdown extension
list lives in one place (FileTypePatterns[FormatMarkdown]).
- Added format_test.go covering IsReadmeFile (mode/symlink/dir
rejection, the directory regression), FileTypePatterns, and GetFormat.
Signed-off-by: Evan Jarrett <evan@evanjarrett.com>