stack overflow if cannot unlink $HOME/.sh_history

It will also fail the rename in the chunk:

src/cmd/ksh93/edit/history.c
"""
unlink(hist_old->histname);
if(access(hist_old->histname,F_OK) >= 0)
{
/* The unlink can fail on windows 95 */
int fd;
char *last, *name=hist_old->histname;
close(sffileno(hist_old->histfp));
tmpname = (char*)malloc(strlen(name)+14);
if(last = strrchr(name,'/'))

{ *last = 0; pathtmp(tmpname,name,"hist",NIL(int*)); *last = '/'; }

else
pathtmp(tmpname,".","hist",NIL(int*));
if(rename(name,tmpname) < 0)

{ free(tmpname); tmpname = name; }

fd = open(tmpname,O_RDONLY);
sfsetfd(hist_old->histfp,fd);
if(tmpname==name)
tmpname = 0;
}
hist_ptr = 0;
if(fstat(sffileno(hist_old->histfp),&statb)>=0)

{ histinit = 1; histmode = statb.st_mode; }

"""

Another condition required is to have a full .sh_history.
This will cause sh_histinit to call hist_trim, that will
again call sh_histinit.

On the backtrace, the condition is verified in the statb
local variable of hist_trim, where the call trace shows that
the unlink and rename syscalls failed.
The unlink call may fail due to a stale file or some filesystem
issue. The rename call will fail if tmpname is on another filesystem;
could be nfs vs local filesystem or local filesystem and a tmpfs /tmp.

The issue only happens if the unlink fails, but still, could use
a smarter or fallback approach to not cause the stack overflow crash.