Improve hg-git's author/committer parsing to match what git expects

[ehsan]

I found out about this problem when converting Mozilla's hg repository to git.

The way that git parses the author/commiter lines is that it looks for the first less-than character, and expects that to start the email address, and then it looks for the next greater-than character, and it then expects everything following that character to be parsed as a date.

hg-git's output doesn't completely match that expectation. For example, for this revision hg.mozilla.org/mozilla-central/rev/a537a070dbf40081e1d32321924b6589b271574e, the author is "Ms2ger@gmail.com", which makes hg-git generate a author line like this:

author Ms2ger@gmail.com none@none 123456000 +0000

Which git fails to parse. Another example is this revision http://hg.mozilla.org/mozilla-central/rev/e88d2327e25d600ce326615f682db1d79d2bb10e, where there is no space between the username and the email, which creates an author line like this:

author Ms2ger<Ms2ger@gmail.com <Ms2gerMs2ger@gmail.com 123456000 +0000

And you can see how that would confuse git!

With the fixes in this pull request, hg-git can generate better commit objects, that git can actually deal with. I managed to convert the entire hg history of mozilla-central to git with these patches.

[ehsan]

ehsan@04a37b4 also fixes another instance of this problem, for commits like https://hg.mozilla.org/mozilla-central/rev/e751acb410d0

[durin42]

Can you add some tests for this? I'm hesitant to pull this without corresponding tests. I'm also skeptical of the correctness of get_valid_git_username_email() - couldn't that fail if the username was something like " foo@example.com " or some other broken thing?

When you're ready, I'd greatly prefer patches mailed to the hg-git Google Group - it's easier for me to review and apply them there than on a pull request here.

Thanks!