git_commit_authors method hangs when git server slows down

[martinsozols]

Hi,

For a while now we noticed that cucumber and rspec test hang for 20 - 30 minutes (sometimes more) at the end of the test run due to our CI system being under heavy load. After investigating found that GitAdapter is running git fetch --shallow-since "one month ago" --quiet 2>/dev/null when env is CI and shallow repository. This adds extra load to system. This call does not time out. knapsack_pro is used in our monorepo that has a very active usage.

Running git fetch --shallow-since "one month ago" --quiet 2>/dev/null directly on CI machines, it runs ~3 minutes

time git fetch --shallow-since "one month ago" --quiet 2>/dev/null

real	3m26.380s
user	4m21.399s
sys	0m50.912s

My guess it that Timeout.timeout does not handle interruption well when our git server slows down.