January 5, 2001 was a Tuesday, not a Friday. Jameson fixed this exact
problem for the multipart test in ec2b0a98cc, but not for
generate_message itself.
As Jameson pointed out in ec2b0a98cc, if we want to test date parsing,
we should do it separately.
Change #!/bin/bash at start of tests to "#!/usr/bin/env bash". That way
systems running on bash < 4 can prepend bash >= 4 to path before
running the tests.
This is part of an effort to avoid proliferation of excessive
top-level notmuch commands. Also, "raw" better captures the
functionality here, (as opposed to "cat" which is a fairly oblique
reference to a bad Unix abbreviation whose metaphor doesn't work here
since "notmuch cat" operates only on a single message and hence cannot
"con'cat'enate" anything).