weird conflicting implementation error

gistfile1.rs

/// A trait for types that can be created from a SQLite value.
pub trait FromSql {
    unsafe fn column_result(stmt: *mut sqlite3_stmt, col: c_int) -> SqliteResult<Self>;
}

impl<'a, T> FromSql for T where T: convert::From<&'a str> {
    unsafe fn column_result(stmt: *mut sqlite3_stmt, col: c_int) -> SqliteResult<T> {
        let c_text = ffi::sqlite3_column_text(stmt, col);
        if c_text.is_null() {
            Ok(T::from(""))
        } else {
            let c_slice = CStr::from_ptr(c_text as *const c_char).to_bytes();
            let utf8_str = str::from_utf8(c_slice);
            utf8_str
                .map(|s| T::from(s) )
                .map_err(|e| SqliteError{code: 0, message: e.to_string()})
        }
    }
}

impl FromSql for time::Timespec {
    unsafe fn column_result(stmt: *mut sqlite3_stmt,
                            col: c_int) -> SqliteResult<time::Timespec> {
        let col_str = FromSql::column_result(stmt, col);
        col_str.and_then(|txt: String| {
            time::strptime(&txt, SQLITE_DATETIME_FMT).map(|tm| {
                tm.to_timespec()
            }).map_err(|parse_error| {
                SqliteError{ code: ffi::SQLITE_MISMATCH, message: format!("{}", parse_error) }
            })
        })
    }
}

// Error:

src/types.rs:178:1: 191:2 error: conflicting implementations for trait `types::FromSql` [E0119]
src/types.rs:178 impl<'a, T> FromSql for T where T: convert::From<&'a str> {
src/types.rs:179     unsafe fn column_result(stmt: *mut sqlite3_stmt, col: c_int) -> SqliteResult<T> {
src/types.rs:180         let c_text = ffi::sqlite3_column_text(stmt, col);
src/types.rs:181         if c_text.is_null() {
src/types.rs:182             Ok(T::from(""))
src/types.rs:183         } else {
                 ...
src/types.rs:208:1: 220:2 note: note conflicting implementation here
src/types.rs:208 impl FromSql for time::Timespec {
src/types.rs:209     unsafe fn column_result(stmt: *mut sqlite3_stmt,
src/types.rs:210                             col: c_int) -> SqliteResult<time::Timespec> {
src/types.rs:211         let col_str = FromSql::column_result(stmt, col);
src/types.rs:212         col_str.and_then(|txt: String| {
src/types.rs:213             time::strptime(&txt, SQLITE_DATETIME_FMT).map(|tm| {
                 ...
error: aborting due to previous error