Fix version string from git for shallow clone (#788)

Also, make msys2 action find git executable

.github/workflows/msys2.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Build, run tests and prepare package
         shell: msys2 {0}
         run: |
-          PATH=$PATH:/c/ProgramData/chocolatey/bin/
+          PATH=$PATH:/c/ProgramData/chocolatey/bin/:/c/Program\ Files/Git/bin/
           ./autogen.sh
           ./configure --enable-static --disable-shared # This is because the libtool helper script doesn't handle UTF-8 filenames correctly
           make LDFLAGS='-all-static' # Otherwise ogg isn't linked statically

configure.ac

@@ -512,7 +512,7 @@ AC_CHECK_PROG(GIT_FOUND,git,yes)
 
 if test x$GIT_FOUND$enable_version_from_git = "xyesyes"; then
 	GIT_COMMIT_TAG=`git -C $srcdir --git-dir=.git describe --tags --exact-match 2>/dev/null`
-	GIT_COMMIT_HASH=`git -C $srcdir --git-dir=.git log -1 --pretty=format:%h 2>/dev/null`
+	GIT_COMMIT_HASH=`git -C $srcdir --git-dir=.git log -1 --pretty=format:%H 2>/dev/null | head -c 8`
 	GIT_COMMIT_DATE=`git -C $srcdir --git-dir=.git log -1 --pretty=format:%cd --date=format:%Y%m%d 2>/dev/null`
 	if test ${#GIT_COMMIT_HASH} = 8 && test ${#GIT_COMMIT_DATE} = 8; then
 		GIT_COMMIT_VERSION_AVAIL=yes