color: support a different color mode when the pager is active MSYS on Windows has a terminal that supports the "win32" color mode (which "auto" properly detects for us). However, a popularily configured pager in that environment (GNU less) only supports the "ansi" color mode. This patch teaches color about a new config option: pagermode. It behaves like "mode" but is only consulted when the pager is active for the current command. MSYS users can now set "pagermode = ansi" and get a colorful experience that just works. Previously, MSYS users would have to live without color when using GNU less as the pager, would have to manually configure the pager to attend every command, or would have gibberish if "ansi" was used without the pager.

pager: ensure wrapped dispatch._runcommand runs before color's An upcoming patch will teach color to potentially act differently if the pager is active. Since both extensions wrap the same function (dispatch._runcommand) to change behavior, we must guarantee that pager's wrapped function runs before color's so color may read the breadcrumb left by pager.

pager: set an attribute on ui indicating that a pager is active A subsequent patch will teach the color extension to do different things depending on whether a pager is active. This patch leaves a breadcrumb on the ui instance to allow it do that that.

extensions: support callbacks after another extension loads An upcoming patch will introduce a dependency between the color and pager extensions. To prepare for this, we teach extensions how to register callbacks that can execute when another extension loads. This patch is based on code provided by Matt Mackall. But significant parts have changed (such as the ability to register multiple callbacks and the change in behavior to always call a callback). I believe that always firing the callback is a good practice. I think the common use for this feature will be for extensions to say "run this one-time setup code, after this other extension if possible." Always running the callback will facilitate this.

log: fix --follow null parent not to include revision 0 If p1 is null, ':.' is translated as '0:null'. But rangeset can't handle null, only revision 0 was visible. Because 'null' should not be listed implicitly, "log --follow" (without -r) should be empty if p1 is null. Test of "hg grep -f" is added for cmdutil.walkchangerevs().

cmdutil: have walkchangerevs utilize common function to build revs

log: extract common part from getgraphlogrevs() and getlogrevs()

graphlog: remove useless check for empty repo when --follow is specified This prepares for extracting common part from getgraphlogrevs() and getlogrevs(). getlogrevs() does not handle empty repo specially. When it was added at d74099ac2ac1, revs were build by old-style query, '.:0'. So I think the purpose of "len(repo) > 0" was to handle the case of . = null. Currently it isn't necessary for 'reverse(:.)', and it does not work if repo is not empty but p1 is null. $ hg up null $ hg glog --follow -T '{rev}:{node|short}\n' o 0:0a04b987be5a The subsequent patch will fix this problem, so drops the wrong version for now.

graphlog: move comment and flag denoting revs might be unsorted This prepares for extracting common part from getgraphlogrevs() and getlogrevs(). "possiblyunsorted" exists only in getgraphlogrevs().

graphlog: remove too early return from getgraphlogrevs() for empty repo Even if repository is empty, null revision should exist.

trydiff: call util.binary in only one place It's practically free to call util.binary on empty or None content. By relying on that, we can replace the current four call sites by one.

trydiff: collect all lossiness checks in one place By having all the checks for lossiness in one place, it becomes much easier to get an overview of the conditions that lead to losedatafn() being called. It also makes it obvious that it can not be called multiple times for a single time (something that was rather tricky to determine before).