discovery: prevent crash caused by prune marker having no parent data
If a marker has no parent information, parents field is set to None, which
caused TypeError. I think this shouldn't normally happen, but somehow
I have such marker in my repo.
#ifndef _HG_BDIFF_H_
#define _HG_BDIFF_H_
struct bdiff_line {
int hash, n, e;
ssize_t len;
const char *l;
};
struct bdiff_hunk;
struct bdiff_hunk {
int a1, a2, b1, b2;
struct bdiff_hunk *next;
};
int bdiff_splitlines(const char *a, ssize_t len, struct bdiff_line **lr);
int bdiff_diff(struct bdiff_line *a, int an, struct bdiff_line *b, int bn,
struct bdiff_hunk *base);
void bdiff_freehunks(struct bdiff_hunk *l);
#endif