tests: make output lines conditional for testing with fsmonitor Repository cloned-bookmark-default and tobundle exist in the working directory of main test repository "repo". We should take care for them, because it is known issue that fsmonitor can't handle nested repositories. These nested repositories are cloned from "repo", and the number of unknown files = files in these repositories (including files under .hg) will be changed easily in the future. But testing with fsmonitor is not ordinary. Therefore, test-bookmarks.t with fsmonitor might be broken silently. This is reason why this patch uses "(glob)" for the number of unknown files in "hg summary" output. BTW, this patch doesn't use .hgignore to make test portable, because .hgignore might cause another issue related to "walk_on_invalidate" configuration of fsmonitor.

tests: add fsmonitor specific output lines at enabling largefiles Temporarily enabling largefiles causes these output lines, only if tests are executed with fsmonitor.

show: document why accidentally quadratic is (probably) acceptable

show: also catch AmbiguousCommand cmdutil.findcmd() can raise this as well. While we'll almost certainly never encounter this in the wild, guard against it regardless.