run-tests: allow different extra weight for slow tests The 'test-check-code-hg.t' file is not big enough to be prioritized properly. As a result my tests run often spend about 15 seconds running only it at the end of its tests run. We make the "slow" mechanism a bit smarter to adjust the extra weight of each category independently in a future patch.

ignore: refactor syntax concatenation This refactors the syntax+rule concatenation logic to be more separated. It determines the syntax and the rule separately and then puts them back together. This will help in a later patch when we want to process just the rule before it gets concatenated.

ignore: refactor file read into a function This refactors the ignore file reading code into a function so that in a future patch we can make it recursive.

import-checker: loop to get list of locally defined modules at first This is a preparation for subsequent patches, which expect that all locally defined (= mercurial specific) modules are already known before examinations. Looping twice for specified modules is a little redundant, but reasonable cost for improvement in subsequent patches.

import-checker: add xargs like mode Before this patch, "import-check.py" is invoked via "xargs" in "test-module-imports.t", but it doesn't ensure that "import-checker.py" is certainly invoked with all mercurial specific files at once. "xargs" may invoke specified command multiple times with part of arguments given from stdin: according to "xargs(1)" man page, this dividing arguments is system-dependent. This patch adds "xargs" like mode to "import-checker.py". This can ensure that "import-checker.py" is certainly invoked with all mercurial specific files at once in "test-module-imports.t". This is assumed by subsequent patches.

store: add comment in _hashencode with reason for skipping the first 5 chars