webcommands: allow hgweb's archive to recurse into subrepos

Currently when obtaining an archive snapshot of a repository via the
web interface, subrepositories are not taken in the snapshot. I
introduce an option, archivesubrepos, which allows this.

mercurial/help/config.txt

@@ -1295,6 +1295,10 @@ The full set of options is:
     (DEPRECATED) Whether to allow .zip downloading of repository
     revisions. Default is False. This feature creates temporary files.
 
+``archivesubrepos``
+    Whether to recurse into subrepositories when archiving. Default is
+    False.
+
 ``baseurl``
     Base URL to use when publishing URLs in other locations, so
     third-party tools like email notification hooks can construct

mercurial/hgweb/webcommands.py

@@ -14,6 +14,7 @@ from common import paritygen, staticfile, get_contact, ErrorResponse
 from common import HTTP_OK, HTTP_FORBIDDEN, HTTP_NOT_FOUND
 from mercurial import graphmod, patch
 from mercurial import help as helpmod
+from mercurial import scmutil
 from mercurial.i18n import _
 
 # __all__ is populated with the allowed commands. Be sure to add to it if
@@ -799,7 +800,11 @@ def archive(web, req, tmpl):
         headers.append(('Content-Encoding', encoding))
     req.header(headers)
     req.respond(HTTP_OK)
-    archival.archive(web.repo, req, cnode, artype, prefix=name)
+
+    ctx = webutil.changectx(web.repo, req)
+    archival.archive(web.repo, req, cnode, artype, prefix=name,
+                     matchfn=scmutil.match(ctx, []),
+                     subrepos=web.configbool("web", "archivesubrepos"))
     return []