Update scmgit to 1.7.0.7.
This fixes http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2542.
Changes since 1.7.0.5:
* "git diff --stat" used "int" to count the size of differences,
which could result in overflowing.
* "git rev-list --abbrev-commit" defaulted to 40-byte abbreviations, unlike
newer tools in the git toolset.
* "make NO_CURL=NoThanks install" was broken.
* An overlong line after ".gitdir: " in a git file caused out of bounds
access to an array on the stack.
* "git config --path conf.var" to attempt to expand a variable conf.var
that uses "~/" short-hand segfaulted when $HOME environment variable
was not set.