Merge branch 'en/ort-perf-batch-11'

Optimize out repeated rename detection in a sequence of mergy operations. * en/ort-perf-batch-11: merge-ort, diffcore-rename: employ cached renames when possible merge-ort: handle interactions of caching and rename/rename(1to1) cases merge-ort: add helper functions for using cached renames merge-ort: preserve cached renames for the appropriate side merge-ort: avoid accidental API mis-use merge-ort: add code to check for whether cached renames can be reused merge-ort: populate caches of rename detection results merge-ort: add data structures for in-memory caching of rename detection t6429: testcases for remembering renames fast-rebase: write conflict state to working tree, index, and HEAD fast-rebase: change assert() to BUG() Documentation/technical: describe remembering renames optimization t6423: rename file within directory that other side renamed