bugreporter@tools-sgebastion-07:~/mediawiki-extensions-CirrusSearch$ git checkout origin/REL1_34
Note: checking out 'origin/REL1_34'.

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HEAD is now at **a86e0a5d**... Merge "Drop HHVM support" into REL1_34

core.abbrev::
	Set the length object names are abbreviated to.  If
	unspecified or set to "auto", an appropriate value is
	computed **based on the approximate number of packed objects**
	in your repository, which hopefully is enough for
	abbreviated object names to stay unique for some time.
	The minimum length is 4.

	if (len < 0) {
		unsigned long count = repo_approximate_object_count(r);
		/*
		 * Add one because the MSB only tells us the highest bit set,
		 * not including the value of all the _other_ bits (so "15"
		 * is only one off of 2^4, but the MSB is the 3rd bit.
		 */
		len = msb(count) + 1;
		/*
		 * We now know we have on the order of 2^len objects, which
		 * expects a collision at 2^(len/2). But we also care about hex
		 * chars, not bits, and there are 4 bits per hex. So all
		 * together we need to divide by 2 and round up.
		 */
		len = DIV_ROUND_UP(len, 2);
		/*
		 * For very small repos, we stick with our regular fallback.
		 */
		if (len < FALLBACK_DEFAULT_ABBREV)
			len = FALLBACK_DEFAULT_ABBREV;
	}