I’ve found the following on ST3 dev, ST3 beta and ST2

Selecting and wrapping the following text

'AAA', 'BBB', 'CCC'

"AAA", "BBB", "CCC"

(AAA), (BBB), (CCC)

{AAA}, {BBB}, {CCC}

[AAA], [BBB], [CCC]

results in

'AAA, BBB, CCC

"AAA, BBB, CCC

(AAA), BBB), CCC)

{AAA}, BBB}, CCC}

[AAA], BBB], CCC]

Notice the missing characters. This happens with longer lines as well, but even with short ones as the above.

(Disregard the following bit, it works as it should when there are no blank lines)

Even stranger, selecting and wrapping

'AAA', 'BBB', 'CCC'
"AAA", "BBB", "CCC"
(AAA), (BBB), (CCC)
{AAA}, {BBB}, {CCC}
[AAA], [BBB], [CCC]

without empty lines, produces

'AAA', 'BBB', 'CCC' "AAA", "BBB", "CCC" (AAA), (BBB), (CCC) {AAA}, {BBB},
{CCC} [AAA], [BBB], [CCC]

i.e. joins the lines, adds commas in various places and wraps them to the ruler.