Apache mod_rewrite directives to change gitweb URLs to gitblit URLs

gerrit_gitblit_rewrite

    RewriteEngine on
    # Rewrite old gerrit gitweb URLs to work with new git.
    # Here are some sample URLs that need to continue to work
    #  https://gerrit.wikimedia.org/r/gitweb?p=mediawiki/extensions/Agora.git;hb=HEAD;
    #  https://gerrit.wikimedia.org/r/gitweb?p=mediawiki/core.git;a=blob_plain;f=languages/messages/MessagesEn.php;hb=HEAD
    #  https://gerrit.wikimedia.org/r/gitweb?p=mediawiki/extensions/examples.git;hb=HEAD;f=BoilerPlate/README;
    #  https://gerrit.wikimedia.org/r/gitweb?p=mediawiki/extensions/ArticleFeedback.git;hb=HEAD;f=modules/jquery.articleFeedback/images/star-new-down.png;a=raw;
    #
    # Notes
    # 1. gitblit requires URL-encoding (%2F) of the slashes in the matched
    # paths to project and file.  The [B] option together with
    # AllowEncodedSlashes does this; it also converts '.' in .git and .php
    # to "%2e" , gitblit accepts this.  (If this causes problems with other URLs
    # you could use
    #   RewriteMap esc int:escape
    # and ${esc:%1} for the paths, and probably have to add [noescape] option).
    # 2. Append an empty query string (which mod_rewrite is smart enough to
    # drop), otherwise the original query string is appended -- mod_rewrite
    # lacks a DiscardQueryString option.
    # 3. We can't have separate RewriteCond for p= and f= because the
    # RewriteRule can only reference matches from the last RewriteCond.
    # (You could use [N] to re-run the rewriting process after rewriting
    # for each parameter ... agggh.)
    # 4. To avoid complicated "p= at start or preceded with ;", stick ';' on front.
    # 5. The semicolon-separated parameters p and f can be in any order, so look
    # for p anywhere and add it back at the front.
    # 6. gitweb parameters not handled: a=<some other action>, hb=<some
    # commit>, and #l123 line number fragment.
    AllowEncodedSlashes NoDecode
    # Rewrite a gitweb project link (no file).
    RewriteCond ;%{QUERY_STRING} !;f=
    RewriteCond ;%{QUERY_STRING} ;p=([^;]*)
    RewriteRule ^/r/gitweb$ https://git.wikimedia.org/summary/%1/HEAD? [R=301,L,B]
    # Rewrite a gitweb file link (project and file, in any order).
    RewriteCond ;%{QUERY_STRING} ;p=([^;]*)
    RewriteCond ;p=%1;%{QUERY_STRING} ^;p=([^;]*).*;f=([^;]*)
    RewriteRule ^/r/gitweb$ https://git.wikimedia.org/raw/%1/HEAD/%2? [R=301,L,B]

For Wikimedia's servers, but may be generally useful.