Contacts import: vCard 2.1: Incorrect unfolding #9647

Prerequisites

• I have searched for duplicate or closed issues
• I can recreate the issue with all plugins disabled

Describe the issue

When importing from vCard 2.1 format, the unfolding is incorrect.

Unfolding is different for v2.1 versus v3.0/v4.0.

The docs (vCard 2.1 specs (section 2.1.3), RFC 822#3.1.1) are somewhat confusing (notably, the examples do not match the description), but they say "Unfolding is accomplished by regarding CRLF immediately followed by a LWSP-char as equivalent to the LWSP-char." (LWSP-char is SPACE or HTAB.)

Example:

BEGIN:VCARD
VERSION:2.1
N:Doe;Jane;;;
FN:Jane Doe
NOTE:an
 example
END:VCARD

Expected result: Note: an example
Actual result: Note: anexample

See also bug report #9531/1, and the corresponding merge request #9637, which fixed a similar bug for v3.0 and v4.0.
See also the same bug in sabre/vobject: sabre/vobject#690.

What browser(s) are you seeing the problem on?

Firefox

What version of PHP are you using?

8.2.20

What version of Roundcube are you using?

master / d31c536

JavaScript errors

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PHP errors

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