svn-patiencediff.zsh

#!/bin/zsh

# see this output:
#   $ svn diff --diff-cmd showargs sa/src/palo/include/sereno/sereno_defs.h
#   Index: sa/src/palo/include/sereno/sereno_defs.h
#   ===================================================================
#   $#=7
#   $1=|-u|
#   $2=|-L|
#   $3=|sa/src/palo/include/sereno/sereno_defs.h    (revision 258787)|
#   $4=|-L|
#   $5=|sa/src/palo/include/sereno/sereno_defs.h    (working copy)|
#   $6=|/home/dgoodell/svn/bodega-dev/.svn/pristine/50/50a9914f087cd2f4758d878df14e15901d04a096.svn-base|
#   $7=|/tmp/svn-vQYxuP|

PRETTY_LEFT="$3"
PRETTY_RIGHT="$5"
LEFT="$6"
RIGHT="$7"

if (( $FORCE_COLOR )) || [[ -t 1 ]] ; then
    COLOR_ARG='--color=always'
else
    COLOR_ARG='--color=never'
fi

git --no-pager diff $COLOR_ARG --no-index --patience "$LEFT" "$RIGHT" | \
    perl -p -e "s{\Q--- a$LEFT\E}{--- a/$PRETTY_LEFT}; s{\Q+++ b$RIGHT\E}{+++ b/$PRETTY_RIGHT};"

Rename this script to svn-patiencediff, make it executable, then in your ~/.subversion/config, set this:

[helpers]
diff-cmd = svn-patiencediff