'svn diff [--git] | svn patch' should preserve svn:mergeinfo changes.
Currently, 'svn diff [--git]' uses the "pretty-printing" logic when an
svn:mergeinfo property is changed:
and 'svn patch' doesn't recognize this syntax. (It does apply other
properties, which are printed using the /^##/-hunks unidiff syntax.)
This could be done by teaching 'svn patch' to parse the mergeinfo
pretty-printing, or by having 'svn diff --git' print both a unidiff
and a pretty-print for svn:mergeinfo.