scmutil: 25% speedup in casecollisionauditor
On a large repository, switching casecollisionauditor to lowercasing all file
names at once rather than one at a time improves hg-add time by 25%.
hg debuginstall
$ hg debuginstall
checking encoding (ascii)...
checking installed modules (*mercurial)... (glob)
checking templates (*mercurial?templates)... (glob)
checking commit editor...
checking username...
no problems detected
hg debuginstall with no username
$ HGUSER= hg debuginstall
checking encoding (ascii)...
checking installed modules (*mercurial)... (glob)
checking templates (*mercurial?templates)... (glob)
checking commit editor...
checking username...
no username supplied (see "hg help config")
(specify a username in your configuration file)
1 problems detected, please check your install!
[1]