git merge algorithm question

[Daniel Biran <dbiran@google.com>]

>> I'm trying to better understand one of the merge algorithms as I had some triumphs and tribulations with using a set of commands during a merge. tldr: can a git merge -s recursive -X patience; // result in a fast-forward merge? will --no-ff stop it
>> 
>> So, the scenario is this:
>> 	- Merging a master branch into a feature branch that is 2+ years old
>> 	- We found this command was more beneficial when merging a large 20k line text file: 
>> 		- git merge -s recursive -X patience master
>> 	- In a recent merge using this approach the reflog shows that the merge was performed using a fast-forward from the feature branch's head
>> 		- 082517-1, feature/branch) HEAD@{23}: merge feature/branch: Fast-forward
>> 
>> 
>> My question is, is it possible for that command to use a fast-forward like this? (or did something else go horribly wrong? possibly an atlassian git GUI tool corrupting the work):
>> 	- If it is possible for the command to fast-forward the merge when making the commit does --no-ff force the command to never use fast-forward in this case
>> 
>> Thanks for the help,
>> Daniel
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