This can make a huge difference on repositories which contain more than 16 pack files, at the expense of additional open file handles. My test case was a ports.git repository with > 60 pack files (these accumulate due to 'got fetch', and 'git repack -a' would condense them). With cache size 16 'got update' in /usr/ports took more than 60 seconds. With cache size 64 the same command took less than 5 seconds. The root cause is probably that mapping and unmapping large files over and over again is expensive on OpenBSD.

These changes are intended to make got more compatible with FreeBSD's Capsicum. ok stsp

ok millert

ok tracey

/usr/src updates have become slower for some reason and my best guess is that caching of packed data has become less effective with df613bb4d8662c28a9888714a80ca572bff9d924 (leaks were subsequently fixed by 2cb49fa8fb84f3a8fc2eb6036a6bd9b64c57e347 and by 0dd5271bd8f2a4f92ac3536fcc493eebc39b86e5)