fix: Don't query the default cache directory when a custom one is set (…

…#285)

The default cache directory is now only queried if no explicit cache
path is given. This is necessary to prevent errors on platforms where
the default cache directory does not exist, like Android.

Signed-off-by: Andrew Gunnerson <[email protected]>

crates/core/src/backend/cache.rs

@@ -237,11 +237,13 @@ impl Cache {
     /// [`CacheBackendErrorKind::NoCacheDirectory`]: crate::error::CacheBackendErrorKind::NoCacheDirectory
     /// [`CacheBackendErrorKind::FromIoError`]: crate::error::CacheBackendErrorKind::FromIoError
     pub fn new(id: RepositoryId, path: Option<PathBuf>) -> RusticResult<Self> {
-        let mut path = path.unwrap_or({
+        let mut path = if let Some(p) = path {
+            p
+        } else {
             let mut dir = cache_dir().ok_or_else(|| CacheBackendErrorKind::NoCacheDirectory)?;
             dir.push("rustic");
             dir
-        });
+        };
         fs::create_dir_all(&path).map_err(CacheBackendErrorKind::FromIoError)?;
         cachedir::ensure_tag(&path).map_err(CacheBackendErrorKind::FromIoError)?;
         path.push(id.to_hex());