Disable changing of target branch in new merge request page when a branch has already been specified
### What does this MR do?
This MR prevents a user from changing the target branch inside a new merge request page if the target branch has already been specified (e.g. from the shortcut in the activity feed). A link to "Change branches" is provided to allow the user to do this properly.
### Why was this MR needed?
If a user attempted to create a merge request from a shortcut with a pre-specified target branch (e.g. `master`), the dropdown would suggest that the user could change the branch. However, this did not actually work due to duplicate data elements (see #1830 for more details), and the target branch would always be set to the original, default branch. This would lead to confusion, potentially causing an improper merge request to be created.
### What are the relevant issue numbers?
Closes#1830
### Screenshot
See merge request !846
Fix Error 500 when one user attempts to access another's personal, internal snippet
### What does this MR do?
This MR fixes an Error 500 that occurred if one user tried to access another's personal, internal snippet. Steps to reproduce:
### Why was this MR needed?
1. Go to `<hostname>/snippets/new`.
2. Select "Internal".
3. Create a snippet. Save the URL (e.g. `<hostname>/snippets/20`)
4. Logout and sign in as another user.
5. Go to the URL in step 3.
### What are the relevant issue numbers?
Closes#1815
See merge request !854
Include non-default ssh key location info
Fixes#875
Provide help for people who aren't SSH-clued by indicating
how to point to key files that have been named something
other than the default. A lot of people seem to assume that
the filename they choose is irrelevant and then wonder why
their private key is not being found by simple 'ssh' commands.
See merge request !507
Refactor and spec line highlighting Javascript
- Replaces the fragile Spinach tests for this feature with Jasmine tests
- The "Don't scroll the page when we click a line number" behavior now works as expected
See merge request !820
Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/875
Provide help for people who aren't SSH-clued by indicating
how to point to key files that have been named something
other than the default. A lot of people seem to assume that
the filename they choose is irrelevant and then wonder why
their private key is not being found by simple 'ssh' commands.
Valery Sizov
Robert Speicher
stanhu
Douwe Maan
Achilleas Pipinellis
Stan Hu
Nicolas
Robert Speicher
Jeff Blaine
Darby
Job van der Voort
Strand McCutchen
karen Carias
Dmitriy Zaporozhets
Jacob Vosmaer
Marin Jankovski
Antonio Huete Jimenez
Hannes Rosenögger
