Right now, upasfs exposes header lines as is, without stripping
out new lines. It also documents that it provides one header per
line in the info file.
As a result, when we get a mail with headers that span lines,
our tools get confused.
These split lines are not semantically meaningful. From RFC5322:
2.2.3. Long Header Fields
Each header field is logically a single line of characters comprising
the field name, the colon, and the field body. For convenience
however, and to deal with the 998/78 character limitations per line,
the field body portion of a header field can be split into a
multiple-line representation; this is called "folding". The general
rule is that wherever this specification allows for folding white
space (not simply WSP characters), a CRLF may be inserted before any
WSP.
As a result, to simplify processing, we should just strip out the
line separators when exposing the headers from upasfs.
e3166b4fe8