fix: Support branches other than master, closes #1

Author: sheerun

README.md

@@ -2,7 +2,7 @@
 
 # git squash [![Maintenance](https://img.shields.io/maintenance/yes/2020.svg?maxAge=2592000)]()
 
-Locally squash commits on a branch without needing to resolve any conflicts.
+Locally squash commits on a branch without resolving any conflicts.
 
 It works just like GitHub's "Squash and merge" or GitLab's "Squash commits".
 

git-squash

@@ -25,7 +25,7 @@ if ! git show-ref "$1" > /dev/null; then
   exit 1
 fi
 
-FIRST_COMMIT_ID=$(git log master.. --no-merges --pretty=format:%h | tail -1)
+FIRST_COMMIT_ID=$(git log $1.. --no-merges --pretty=format:%h | tail -1)
 
 if [ "$FIRST_COMMIT_ID" == "" ]; then
   echo "There are no changes to be squashed"