Summary

On different pages there are different month abbreviations used in date displaying and date pickers.

Environment

Jira Core 7.13.0, Jira Core 8.0.0-m0021

Steps to Reproduce

1. Start Jira Core 7.13.0 with: mvn amps:run-standalone -Dproduct=jira -Dproduct.version=7.13.0
2. Setup Jira with defaults and create sample project and issue
3. Got to user preferences and switch language to: Deutsch (Deutschland)
4. Navigate to sample issue detailed view (e.g. http://localhost:2990/jira/browse/DEMO-1)
5. Click Edit and set due date to 10.03.2019. After selecting in date picker the input value is 10/Mrz/19 (screenshot1)
6. Save Issue. On issue view you can see due date as 10/Mär/19 (screenshot2)
7. Go to project versions administration view (e.g. http://localhost:2990/jira/plugins/servlet/project-config/DEMO/administer-versions?status=unreleased)
8. Add new version with start date equal;l to 10.03.2019. After selecting in date picker the input value is 10/mär/19. (screenshpot3)
9. Save version. On version list you can see start date as 10/Mär/19 (screenshot4)

Expected Results

Different pages and components use different formats: 10/Mrz/19,  10/Mär/19, **10/mär/19

Actual Results

All dates in Jira system for logged-in user should use the same format, language and month names/abbreviations. E.g. Jira should use everywhere on pages and in components: 10/Mär/19

Workaround

None

Quick investigation

On Jira issue view:
console.log(Calendar._SMN) > ["Jan", "Feb", "Mrz", "Apr", "Mai", "Jun", "Jul", "Aug", "Sep", "Okt", "Nov", "Dez"]

On project versions administration view:
console.log(Calendar._SMN) > ["Jan", "Feb", "Mär", "Apr", "Mai", "Jun", "Jul", "Aug", "Sep", "Okt", "Nov", "Dez"]