[texhax] unspace already defined

[Nicholas Cole]

Dear All,

I am trying to build a project using the historian package and
biblatex. It is an old project and used to build without a problem,
but now fails with the following error

Document Class: report 2007/10/19 v1.4h Standard LaTeX document class
(/usr/local/texlive/2010/texmf-dist/tex/latex/base/size11.clo))
(/usr/local/texlive/2010/texmf-dist/tex/latex/fancyhdr/fancyhdr.sty)
(/usr/local/texlive/2010/texmf-dist/tex/generic/babel/babel.sty
(/usr/local/texlive/2010/texmf-dist/tex/generic/babel/greek.ldf
(/usr/local/texlive/2010/texmf-dist/tex/generic/babel/babel.def)
Loading the definitions for the Greek font encoding
(/usr/local/texlive/2010/texmf-dist/tex/generic/babel/lgrenc.def))
(/usr/local/texlive/2010/texmf-dist/tex/generic/babel/english.ldf)
(/usr/local/texlive/2010/texmf-dist/tex/generic/babel/english.ldf))
(/usr/local/texlive/2010/texmf-dist/tex/latex/csquotes/csquotes.sty
(/usr/local/texlive/2010/texmf-dist/tex/latex/etoolbox/etoolbox.sty
(/usr/local/texlive/2010/texmf-dist/tex/latex/etex-pkg/etex.sty))
(/usr/local/texlive/2010/texmf-dist/tex/latex/graphics/keyval.sty)
(/usr/local/texlive/2010/texmf-dist/tex/latex/csquotes/csquotes.def)
(/usr/local/texlive/2010/texmf-dist/tex/latex/csquotes/csquotes.cfg))
(/Users/nicholas/Library/texmf/tex/latex/biblatex/biblatex.sty
(/usr/local/texlive/2010/texmf-dist/tex/latex/base/ifthen.sty)
(/usr/local/texlive/2010/texmf-dist/tex/latex/url/url.sty)

! LaTeX Error: Command \unspace already defined.
               Or name \end... illegal, see p.192 of the manual.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...

l.1283   \fi}

I recently upgraded my TeXLive packages, and perhaps that is what has
introduced this error.

Has anyone encountered this issue, and does it have an easy solution?

I'd be very grateful for any help.

Best wishes,

Nicholas