Move plugin_push_current() before svn_binary() in svn_call()
Move plugin_push_current() before svn_binary() in svn_call()

Move the call to plugin_push_current() to be before the first call
to svn_binary() to ensure that svn_binary()'s calls to
plugin_config_get() retrieve the options from SourceSVN's config
options rather than any plugin inheriting from SourceSVN

Fixes #242

Backported from c88f88c97f9dae75cb3e86a005741212ea4c7ade

make-all/source-integration,dregad/source-integration,dregad/source-integration,make-all/source-integration,make-all/source-integration,dregad/source-integration,mantisbt-plugins/source-integration,mantisbt-plugins/source-integration,mantisbt-plugins/source-integration