When `r3_node_find_common_prefix()` searches for the common prefix it
selects the first matched edge, which might not be the best match.
This issue gives memoryleaks which can be viewed in legacy
testcase `check_tree::test_insert_pathl()` by building using:
`CFLAGS="-fno-omit-frame-pointer -fsanitize=leak" cmake ..`
See testcase procedures:
ret = r3_tree_insert_path(n, "/foo/{id}", NULL);
..
ret = r3_tree_insert_path(n, "/foo/{idx}/{idy}", NULL);
..
ret = r3_tree_insert_path(n, "/foo/{idx}/{idh}", NULL); <-- leaks
Also added a testcase that triggers the problem including a leak for
reproduction on baseline.
ff1ef2c148