Updates for 7.13 stable (RC4)



See merge request !1012

This reverts commit fbdaf0e2.

The existing behavior of the backups is to overwrite whatever data
was still there in the scratch directories. This broke when we added
a 'gzip' step because 'gzip database.sql' will fail if 'database.sql.gz'
already exists. Doing 'rm -f database.sql.gz' before the 'gzip'
avoids this failure.

Closes #2009

Closes #2001

Recalculating graph_log took minutes on a large repository since each
of the 6000 commits would need to calculate the diff. Since graph_log
does not appear to be used, remove it from the list of things to update.
For the Linux kernel repository, this reduced the ProjectCacheWorker time
from 8+ minutes to 16 seconds.

Closes #2016

This reverts commit ebb6393d.

Fixes from master to 7.13.rc3



See merge request !1001

This reverts commit 94c2516a, reversing
changes made to ae44e5ec.

Closes #2008

Closes #2002

Merge branch 'advanced-cache' into 'master'

Backport to stable from merge request !986

- - -

Advanced cache

Fixes #1993

* Build missing cache values in background job after each push
* Store commit_count in project table. Refresh in background job
* moved repository size calculation in background job


## Advantages

Every time push is triggered - we build cache for project even without user visiting project page. 
That means first visit is as fast as others now. This is especially good for active projects where people have some requests fast because of cache and some slow - because cache was build in their request. 

Between cache expired and cache built we we had gap when Linux repo can give 502 error because calculation commits count takes 30 seconds or even more. 
Using value from database fix this problem. Before cache is updated you see old value from database. After - you see new one. 

Basically this merge request is super win to GitLab. We don't do some heavy operations in user request but instead in background job. 

## Temporary problem

After this migration all projects will have `0` commits in database. It fill be replaced with real value on next push. I did not add recalculation to migration because it will last forever on big instances.  Can be fixed by adding rake task which will go in background on live instance without downtime



See merge request !989

Advanced cache

Fixes #1993

* Build missing cache values in background job after each push
* Store commit_count in project table. Refresh in background job
* moved repository size calculation in background job


## Advantages

Every time push is triggered - we build cache for project even without user visiting project page. 
That means first visit is as fast as others now. This is especially good for active projects where people have some requests fast because of cache and some slow - because cache was build in their request. 

Between cache expired and cache built we we had gap when Linux repo can give 502 error because calculation commits count takes 30 seconds or even more. 
Using value from database fix this problem. Before cache is updated you see old value from database. After - you see new one. 

Basically this merge request is super win to GitLab. We don't do some heavy operations in user request but instead in background job. 

## Temporary problem

After this migration all projects will have `0` commits in database. It fill be replaced with real value on next push. I did not add recalculation to migration because it will last forever on big instances.  Can be fixed by adding rake task which will go in background on live instance without downtime

See merge request !986

Time ago fix for compare page



See merge request !1905

7-13 stable: changelog update



See merge request !1901

This reverts commit 8a01a122.

fixed notifications title

I fixed the title and link to this document because I believe that it's more clear and easier to find if it has "emails" in the name.


See merge request !1897

Fix path to move_drop_indexes.ed

Small documentation fix.

See merge request !1900