largefiles: avoid redundant changectx looking up at each repetitions These code paths look up changectx at each repetitions, even though the changectx key isn't changed while loop.

largefiles: omit updating newly added standin at linear merging Updating standin for newly added largefile is needed, only if same name largefile exists in destination context at linear merging. In such case, updated standin is used to detect divergence of largefile at overridefilemerge(). Otherwise, standin doesn't have any responsibility for its content (usually, it is empty).

largefiles: reuse hexsha1() to centralize hash calculation logic into it This patch also renames argument of hexsha1(), not only for readability ("data" isn't good name for file-like object), but also for reviewability (including hexsha1() code helps reviewers to confirm how these functions are similar). BTW, copyandhash() has also similar logic, but it can't reuse hexsha1(), because it writes read-in data into specified fileobj simultaneously.

py3: prove second commit works Finally it works.

py3: fix manifestdict.fastdelta() to be compatible with memoryview This doesn't look nice, but a straightforward way to support Python 3. bytes(m[start:end]) is needed because a memoryview doesn't support ordering operations. On Python 2, m[start:end] returns a bytes object even if m is a buffer, so calling bytes() should involve no additional copy. I'm tired of trying cleaner alternatives, including: a. extend memoryview to be compatible with buffer type => memoryview is not an acceptable base type b. wrap memoryview by buffer-like class => zlib complains it isn't bytes-like

crecord: use ProgrammingError