Second line is matching with multiline option when trying to match start of entire input

[learnbyexample]

What version of ripgrep are you using?

ripgrep 12.1.1 (rev 7cb211378a)

How did you install ripgrep?

Using ripgrep_12.1.1_amd64.deb

What operating system are you using ripgrep on?

Ubuntu 20.04 LTS

Describe your bug.

Was trying to create an example to show difference between \A and ^ anchors when multiline option is enabled. For certain input, \A is matching second line content.

What is the actual behavior?

Example with \A string anchor. The last command gives no output as expected.

$ printf '1\nbaz\nabc\n' | rg -U '\Ab'
baz
$ printf '12\nbaz\nabc\n' | rg -U '\Ab'
baz
$ printf '123\nbaz\nabc\n' | rg -U '\Ab'
$ 

Same thing seen with ^ anchor and m flag disabled:

$ printf '1\nbaz\nabc\n' | rg -U '(?-m)^b'
baz
$ printf '12\nbaz\nabc\n' | rg -U '(?-m)^b'
baz
$ printf '123\nbaz\nabc\n' | rg -U '(?-m)^b'
$ 

What is the expected behavior?

Second line shouldn't match for above cases.

[BurntSushi]

I beat you to it: #1878 :-)

Fix is on master.

[learnbyexample]

Wow, you saw the comment, filed an issue and fixed it while I was still trying to generate more test cases (I was about to edit my issue to add those when I saw it was closed already!).