Log Message:
Update to 1.6.4, because previous versions are mentioned in
pkg-vulnerabilities.

Changes since 1.6.3:
This is a monthly bugfix release.

    * archive: set date to 1980 for very old zip files
    * bookmarks: fix _bookmarks/lookup() reentrancy issue (issue2016)
    * color: add win32 support for non-black background
    * context: fix filectx.undelete() (issue2388)
    * convert/darcs: handle non-ASCII metadata in darcs changelog (issue2354)
    * convert/svn: fix broken symlink renames in svn sink
    * core: use lexists() instead of exists() where appropriate
    * hgweb: Fix memory leak when using hg commands over http repositories
    * hgweb: correct Content-Type header values for archive downloads
    * log: include unmodified-in-merge files in log diff/stat (issue2383)
    * mq: always require --force when pushing patches (issue2363)
    * patch: do not overwrite broken untracked symlinks
    * patch: fix rename text to binary file (issue2400)
    * patch: fix target when patching broken symlinks (issue2368)
    * patch: upgrade to git patch when removing binary file
    * rename: do not overwrite existing broken symlinks
    * url: verify correctness of https server certificates (issue2407)
    * util: avoid using hashlib on Python < 2.5 (issue2278)
    * verify: fix "missing revlog!" errors for revlog format v0 and \ 
add test
    * win32: add Emacs scripts to Inno Setup installer
    * win32: add hgweb scripts to Inno Setup installer