tests: don't use /dev/urandom for largefiles testing There is no need to use entropy here just to create some content that only will be used for hashing and ignored. This avoids a problem where dd from /dev/urandom on solaris generates too short output.

encoding: protect against non-ascii default encoding If the default python encoding was changed from ascii, the attempt to encode as ascii before lower() could throw a UnicodeEncodeError. Catch UnicodeError instead to prevent an unhandled exception.

update: fix case-collision with a clean wd and no --clean cbf2ea2f5ca1 introduced some logic to avoid case-collision detection between source and destination revisions when it does not make sense: clean or to be cleaned working directories. Unfortunately, part of it was flawed and the related test was broken by another bug. This patch disables cross revision case collision detection for updates without option or with --check, if the working directory is clean.

update: make --check abort with dirty subrepos Aka "we could use dirty() but... yeah let's use it"