latexdiff produces latex with error: ! Illegal parameter number in definition of showCODEN

I am using latexdiff to generate a diff latexdiff-vc --git --flatten -r TAG paper.tex.

Unfortunately, when I try to compile a PDF, I get the following error

! Illegal parameter number in definition of showCODEN.
<to be read again>
                   1
l.1003 ...undefined def showCODEN     DIFadd{#1
                                                  }{unskip}     fi
?

The generates latex looks something like

%DIF > %% ====================================================================
%DIF > %% NOTE TO THE USER: you can override these defaults by providing
%DIF > %% customized versions of any of these macros before the bibliography
%DIF > %% command.  Each of them MUST provide its own final punctuation,
%DIF > %% except for shownote{}, showDOI{}, and showURL{}.  The latter two
%DIF > %% do not use final punctuation, in order to avoid confusing it with
%DIF > %% the Web address.
%DIF > %%
%DIF > %% To suppress output of a particular field, define its macro to expand
%DIF > %% to an empty string, or better, unskip, like this:
%DIF > %%
%DIF > %% newcommand{showDOI}[1]{unskip}   % LaTeX syntax
%DIF > %%
%DIF > %% def showDOI #1{unskip}           % plain TeX syntax
%DIF > %%
%DIF > %% ====================================================================

ifx showCODEN    undefined def showCODEN     DIFadd{#1}{unskip}     fi
ifx showDOI      undefined def showDOI       DIFadd{#1}{{tt DIFadd{DOI:}}penalty0{#1}DIFadd{ }}
  fi
ifx showISBNx    undefined def showISBNx     DIFadd{#1}{unskip}     fi
ifx showISBNxiii undefined def showISBNxiii  DIFadd{#1}{unskip}     fi
ifx showISSN     undefined def showISSN      DIFadd{#1}{unskip}     fi
ifx showLCCN     undefined def showLCCN      DIFadd{#1}{unskip}     fi
ifx shownote     undefined def shownote      DIFadd{#1}{DIFadd{#1}}          fi
ifx showarticletitle undefined def showarticletitle DIFadd{#1}{DIFadd{#1}}   fi
ifx showURL      undefined def showURL       DIFadd{#1}{DIFadd{#1}}          fi

bibitem{Baldonado-2000}
{DIFadd{Michelle Q.~Wang Baldonado}}DIFadd{, }{DIFadd{Allison Woodruff}}DIFadd{, }{DIFadd{and}} {DIFadd{Allan Kuchinsky}}DIFadd{.
  2000.
}newblock showarticletitle{Guidelines for Using Multiple Views in Information
  Visualization}DIFadd{. In }{em DIFadd{Proceedings of the working conference on Advanced
  visual interfaces, }{DIFadd{AVI}} DIFadd{2000, Palermo, Italy, May 23-26, 2000}}DIFadd{. 110--119.
}newblock
showDOI{%
url{http://dx.doi.org/10.1145/345513.345271}}

How to I manually fix the code to resolve the error?