Add fetch option for topic branch finish

[alexrinass]

Add support for fetching from remote before finishing a topic branch, which ensures the latest remote changes are incorporated in the merge.

• Add command line options to control fetching before branch finish:
  • --fetch - Fetch from remote before finishing branch
  • --no-fetch - Explicitly disable fetching
• Ensure the git config setting is respected for each topic branch type individually
  • Generic key: gitflow.<topic>.finish.fetch
  • Examples: gitflow.feature.finish.fetch, gitflow.release.finish.fetch, gitflow.hotfix.finish.fetch
• When fetch is enabled, perform a git fetch operation on the relevant remote before merging the branch
  • Example: git fetch <remote> before executing the merge and cleanup operations
• Default to no-fetch when config setting is not present
• Update documentation to reflect the new option
• Add tests to verify the option works correctly for each branch type
• For testing purposes, you can use another local bare repo as “remote” by using its file URL

Test Cases:

1. Default Behavior (No Fetch)

   • Create changes on remote that aren't in the local repo
   • Finish a branch without specifying fetch option
   • Expected: Branch is finished based on local state, without remote changes
   • Verify merge doesn't include the remote changes

2. Fetch with Command Line (Positive)

   • Create changes on remote that aren't in the local repo
   • Test with command line: git flow feature finish myfeature --fetch
   • Expected: Fetch occurs before finishing the branch
   • Verify merge includes the latest remote changes

3. Fetch with Command Line (Negative)

   • Create changes on remote that aren't in the local repo
   • Set config: gitflow.feature.finish.fetch=true
   • Test with command line: git flow feature finish myfeature --no-fetch
   • Expected: No fetch occurs despite config setting
   • Verify merge doesn't include the remote changes

4. Fetch with Config

   • Create changes on remote that aren't in the local repo
   • Set config: gitflow.feature.finish.fetch=true
   • Finish a branch without specifying fetch option
   • Expected: Fetch occurs before finishing the branch
   • Verify merge includes the latest remote changes

5. Cross-Branch Type Tests

   • Verify fetch works correctly for feature, release, and hotfix branches
   • Test both positive and negative command line options
   • Test with different configs for each branch type

[linear]

TOWR-34 Implement fetch option for branch finish

Add support for fetching from remote before finishing a topic branch, which ensures the latest remote changes are incorporated in the merge.

• Add command line option to fetch before finishing a branch (--fetch)
• Ensure the git config setting is respected for each topic branch type individually
  • Generic key: gitflow.<topic>.finish.fetch
  • Examples: gitflow.feature.finish.fetch, gitflow.release.finish.fetch, gitflow.hotfix.finish.fetch
• When fetch is enabled, perform a git fetch operation on the relevant remote before merging the branch
  • Example: git fetch <remote> before executing the merge and cleanup operations
• Default to no-fetch when config setting is not present
• Update documentation to reflect the new option
• Add tests to verify the option works correctly for each branch type