shelve: add "writebundle()" to invoke "writebundle()" with relative path and vfs

shelve: add "applybundle()" to invoke "readbundle()" with relative path and vfs "applybundle()" also includes "addchangegroup()" invocation to encapsulate "vfs.join()" inside it.

bundlerepo: treat temporarily extracted bundle file via vfs

vfs: add "mkstemp()"

repair: make "strip()" treat bundle files via vfs This patch makes "repair.strip()" treat bundle files via vfs. This patch also avoids applying "vfs.join()" on the value returned by "changegroup.writebundle()", to get relative path from "_bundle()".

changegroup: add "vfs" argument to "readbundle()" to pass relative filename

repair: make paths in "_bundle()" relative to ".hg" This patch makes paths below in "_bundle()" relative to ".hg": - backup directory ("strip-backup"), and - bundle file under backup directory "vfs" is passed to "changegroup.writebundle()" to use relative path directly. This patch applies "vfs.join()" on the value returned by "_bundle()", because the caller expect it to return absolute path. This will be changed by succeeding patch changing the caller side.

changegroup: add "vfs" argument to "writebundle()" for relative access via vfs Before this patch, filename specified to "changegroup.writebundle()" should be absolute one. In some cases, they should be relative to repository root, store and so on (backup before strip, for example). This patch adds "vfs" argument to "writebundle()", and makes "writebundle()" open (and unlink) "filename" via vfs for relative access, if both filename and vfs are specified.

localrepo: make "undofiles()" return list of tuples "(vfs, relative filename)" Before this patch, "localrepository.undofiles()" returns list of absolute filename of undo files. This patch makes it return list of tuples "(vfs, relative filename)" to access undo files via vfs. This patch also changes "repair.strip()", which is the only user of "localrepository.undofiles()".

exchange: fix pyflakes import complaint