trydiff: extract function that generates filename pairs The code that identifies copies/renames, as well as the filenames before and after, is now isolated and we can extract it to a function so it can be overridden by extensions (in particular the narrow clone extension).

trydiff: read file data in only one place This moves getfilectx() out of the initial block in the loop, leaving that block to be only about finding pairs of filenames in ctx1 and ctx2 to diff.

trydiff: set filename variables to None even when not opts.git or losedatafn There is not much left of the first block "if opts.git or losedatafn" block now. The next patch will move the call to getfilectx() out of that block. We will then be using the defined-ness of 'f1' to tell whether the file existed in ctx1 (and under what name). We will need this information whether or not opts.git or losedatafn was set, so just remove that guard. The only operation in the block that is not cheap is the call to getfilectx(), but that has an extra 'if opts.git' guard already. --ignore-space-change proves that only 'if opts.git or losedatafn:' was removed.

trydiff: read flags in one place Now that we can trust f1/f2 to indicate whether that side of the diff exists, we can move the calls to ctx.flag() to a single place.

trydiff: break 'if opts.git or losedatafn' into two This moves the initialization 'binary' closer to its other assignment, but exists mostly to simplify future patches.

trydiff: make filenames None when they don't exist f1 and f2 are currently set always set to some filename, even for added or deleted files. Let's instead set them to None to indicate that one side of the diff doesn't exist. This lets us use the filename variables instead of the content variables and simplify a bit since the empty string is not a valid filename. More importantly, it paves the way for further simplifications.

test-help: add test to demonstrate that 'hg help merge-tools' is sane

help.merge-tools: do not double document merge tools Merge tools were being double documented in help system output due to functions being defined under multiple names in the merge tools dictionary. Establish a new dictionary for just the tools to document and use it from the help system so we don't get double output. Double documentation likely plagues other auto-documented items as well. It might be a good idea to eventually compare function instances to filter out duplicate entries from dictionaries passed to ``makeitemsdoc``. However, without an easy way to break ties, this may result in some functions being advertised over their modern equivalents. This would be a noble patch series. But it isn't one this author is willing to tackle at this time.

help: teach topic symbols how to dedent When using docstrings for documenting symbols such as revsets, templates, or hgweb commands, documentation likely has leading whitespace corresponding to the indentation from the Python source file. Up until this point, the help system stripped all leading and trailing whitespace and replaced it with 2 spaces of leading whitespace. There were a few bad side-effects. First, sections could not be used in docstrings because they would be indented and the rst parser would fail to parse them as sections. Also, any rst elements that required indentation would lose their indentation, again causing them to be parsed and rendered incorrectly. In this patch, we teach the topic symbols system how to dedent text properly. I argue this mode should be enabled by default. However, I stopped short of changing that because it would cause a lot of documentation reformatting to occur. I'm not sure if people are relying on or wanting indentation. So, dedenting has only been turned on for hgweb symbols. This decision should be scrutinized.

webcommands: document "graph" web command