README

manifest/revlog: do not let the revlog cache mutable objects

If a buffer of an mutable object is passed to revlog.addrevision(), the revlog
will happily store it in its cache. Later when the revlog reuses the cached
entry, if the manifest modified the object in-between, all kind of bugs
appears.

We fix it by:
- passing immutable objects to addrevision() if they are already available
- only storing the text in the cache if it's of str type

Then we can remove the conversion of the cache entry to str() during
retrieval. That was probably just there hiding the bug for the common cases
but not really fixing it.

Basic install:

 $ make            # see install targets
 $ make install    # do a system-wide install
 $ hg debuginstall # sanity-check setup
 $ hg              # see help

See http://mercurial.selenic.com/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.