In-browser editor replace the eol at the end of file with LF regardless of existing eol type

Summary

Bitbucket Server in-browser editor unexpectedly replaces CRLF at the end of file with LF.

Environment

• Bitbucket Server 4.13 or newer versions
  • Verified with v5.5.5 hosted on Ubuntu 14.04.5 LTS and Git version 2.13.0

Steps to Reproduce

1. (Local) Create a file containing lines with CRLF

   # The special character "\r\n" stands for CRLF. And "\c" suppresses newline
   $ echo -e "North\r\nSouth\r\nWest\r\n\c" > example.txt
   # Verify the file ends with "^M$"
   $ cat -e example.txt
   North^M$
   South^M$
   West^M$
   # Verify the file ends with "0d 0a" in hexadecimal binary
   $ hexdump -C example.txt
   00000000  4e 6f 72 74 68 0d 0a 53  6f 75 74 68 0d 0a 57 65  |North..South..We|
   00000010  73 74 0d 0a                                       |st..|
   00000014
   

1. (Local) Git commit and push the file to Bitbucket Server
2. (Remote) Open example.txt and add "East" to the second line by in-browser editor
3. (Local) Git pull
4. (Local) Check the eol type at end of file is changed to LF from CRLF

   # Verify the file ends with "$" but not "^M$"
   $ cat -e example.txt
   North^M$
   East^M$
   South^M$
   West$
   # Now the file ends with "0a" in hexadecimal binary
   $ hexdump -C example.txt
   00000000  4e 6f 72 74 68 0d 0a 45  61 73 74 0d 0a 53 6f 75  |North..East..Sou|
   00000010  74 68 0d 0a 57 65 73 74  0a                       |th..West.|
   00000019
   

Expected Results

The edited file keeps CRLF at the end of file:

$ cat -e example.txt
North^M$
East^M$
South^M$
West^M$

Actual Results

CRLF at the end of file is replaced with LF.

$ cat -e example.txt
North^M$
East^M$
South^M$
West$

Notes

• Owing to these configurations in git, other lines except the end of file are intact
  • core.autocrlf=input
  • core.safecrlf=warn
• In-browser editor inserts newline (LF) when the file doesn't contain eol character

  echo 'Foo\c' > example.txt
  

Workaround

• Edit files in other editor but not in-browser editor if you want to keep CRLF