stringutil: improve check for failed mailmap line parsing
The existing check for a bad mailmap file entry fails with inputs
like b'>@<'. This commit adds a function to check if a sufficient
amount of information has been parsed from a mailmap file entry.
At minimum, one email must be found (assumed to be the commit email).
If email is not empty and no names are found, then there must be
two emails. If there are at least one email and name, the mapping
is valid.
Differential Revision: https://phab.mercurial-scm.org/D3003
$ hg init repo
$ cd repo
$ touch foo
$ hg ci -Am 'add foo'
adding foo
$ hg up -C null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
this should be stored as a delta against rev 0
$ echo foo bar baz > foo
$ hg ci -Am 'add foo again'
adding foo
created new head
$ hg debugindex foo
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 0 ..... 0 b80de5d13875 000000000000 000000000000 (re)
1 0 13 ..... 1 0376abec49b8 000000000000 000000000000 (re)
$ cd ..