I used to find it unnatural too. Recently, I changed my working habits so that I keep a running todo list of things I'm working on. When I complete a task, the todo becomes the commit message, and I leave it in present tense.
Other reasons to prefer it:
* It's generally shorter than the alternatives: "Implement" versus "Will implement", "implements", or "implemented".
* I think it's actually more accurate to say that commit messages should be in the imperative mood, not the present tense. The message is basically telling some unspecified agent to do something "Fix this bug." That lines up with the imperative form we use to write a lot of code.
Other reasons to prefer it:
* It's generally shorter than the alternatives: "Implement" versus "Will implement", "implements", or "implemented".
* I think it's actually more accurate to say that commit messages should be in the imperative mood, not the present tense. The message is basically telling some unspecified agent to do something "Fix this bug." That lines up with the imperative form we use to write a lot of code.