Fix the 'svnadmin load' part of issue #4476 "Mergeinfo containing r0 makes svnsync and svnadmin dump fail".
Make 'svnadmin load' accept mergeinfo containing r0 (with a warning) if the option to validate properties is not enabled. In that case that mergeinfo property will not be adjusted for revision numbers or paths. Add a test.
* subversion/include/svn_repos.h (svn_repos_notify_warning_t): Add a new value for invalid mergeinfo.
* subversion/libsvn_repos/load-fs-vtable.c (adjust_mergeinfo_property): New, factored out of ... (set_node_property): ... here. If adjusting the mergeinfo fails, return an error if validating properties, or give a warning and use the invalid value otherwise.
* subversion/tests/libsvn_repos/dump-load-test.c (test_dump_bad_props): New, factored out of... (test_dump_r0_mergeinfo): ... here. (test_load_bad_props, load_r0_mergeinfo_notifier, test_load_r0_mergeinfo): New. (test_funcs): Add the new test.
Stop re-using a single notify struct while loading a repository from a dumpfile. While nice in theory it is easy to forget clearing out variables in the struct, which our bindings then try to read on the next invocation.
As temporary -but safe to backport- intermediate step introduce a scratch/ iter pool to hold the notification struct, while the code doesn't have proper scratch pools yet.
This resolves a segfault in the JavaHL tests on OpenBSD Found by: stsp