Why does path-restricted 'git log' omit merge commits with interesting conflict resolutions?

Question

If a file's history includes a merge commit with an "interesting" conflict resolution, git log will skip over it. Why is this, and how can I make that commit be included?

(By "interesting", I mean a resolution that doesn't just take the version from HEAD or MERGE_HEAD verbatim.)

For example, in this sample repository, I've prepared a simple history that illustrates the problem:

$ git log --oneline --graph 
* 4a69f452 add -stuff at C and G
*   9fc8e8bf resolve E-alpha + E-beta as E-gamma
|\  
| * 95bc62e9 add -beta suffix on lines E and J
* | 465abd9e add -alpha suffix on lines A and E
|/  
* f43dc68c initial ten-line A..J file

The merge commit resolved the conflict by introducing an entirely new version of the E line:

$ git show 9fc8e8bf -U0 | grep -A100 ^@@
@@@ -5,1 -5,1 +5,1 @@@
- E-alpha
 -E-beta
++E-gamma

However, git log totally glosses over this. The commits it lists fail to explain the current state of the E line in test.txt:

$ git log --oneline 4a69f452 test.txt
4a69f452 add -stuff at C and G
95bc62e9 add -beta suffix on lines E and J
465abd9e add -alpha suffix on lines A and E
f43dc68c initial ten-line A..J file

Is there an option I can give to git log that will make it include the merge commit?

Other commands, like git blame, do show that the E line was last touched in the 9fc... merge commit:

$ git blame -L5,5 4a69f452 test.txt
9fc8e8bf9 (Matt McHenry 2016-12-28 16:55:10 -0500 5) E-gamma

(Note: the above outputs are produced by git version 2.11.0.)

Answer 1

This happens if you have the log.follow config option set to true or, equivalently, if you pass --follow to the log command.

The documentation for this option says it "does not work well on non-linear history". I guess this is what they mean. :(

$ git log --oneline 4a69f452 -- test.txt
4a69f45 add -stuff at C and G
9fc8e8b resolve E-alpha + E-beta as E-gamma
95bc62e add -beta suffix on lines E and J
465abd9 add -alpha suffix on lines A and E
f43dc68 initial ten-line A..J file

---

$ git log --oneline 4a69f452 --follow -- test.txt
4a69f45 add -stuff at C and G
95bc62e add -beta suffix on lines E and J
465abd9 add -alpha suffix on lines A and E
f43dc68 initial ten-line A..J file